Depressed over daughter's mental/physical issues

Have you looked into the Special Recreation Association in your area? I used to work at a couple different ones & besides being great for the kids it provided a much needed respite for their parents. Depending on how large your SRA is, they might offer programs a couple times a week up to 6 days a week and several times a day. The cost is usually nominal as it is subsidized by the county. You can contact your local park district for information.
The good ones don't just focus on recreation, but also plan fun education activities centered around participants' needs. I think it would probably be a good idea to mention again to her pediatrician & also might be worth contacting your local school district for additional testing. Maybe there is something else now going on, or at a minimum they might be able to offer additional suggestions for homeschooling or public resources. I used to teach & know that some homeschooled special ed children would come in 3x/week for an hour or two of special services -- I don't think that's commonly offered, but I mention it only to say that you never know what the school district might be able to suggest. They are required to manage an IEP for all children in their district even if the children attend private school or are homeschooled. The services are free, so be sure to take advantage of them.
Also, the school might be able to connect you with a support group for other moms with special needs children. Other parents can be the very best sources of ideas & also offer emotional support. Finally, I'm not sure what would help with the sensory processing, but the separation anxiety is something that a warm, caring, experienced teacher should be able to manage. Over my career, I taught children ranging from age 5 to age 17. Though in the Kindergarten classes I had many more children who struggled with separating from parents, I dealt with that issue at all levels. There are methods to help children feel comfortable in school & to resolve fears within the first week of school. But not knowing your neighborhood school, perhaps such a teacher hasn't been available to your child. Don't give up hope, though. I have seen children comfortably transition to a school setting in 4th grade, in middle school, or even in high school, once a caring and well-trained teacher became available. Perhaps that is something to look into again -- if not for this school year, perhaps for the next one (or for summer school, as a trial run). Besides traditional schooling, some districts can provide a traveling professional teacher to work with your child in your home. Testing must demonstrate a need for that & not every district has funds for it, but sometimes even the poorest districts can get grants (if they agree your daughter needs it, there are grant writing courses online & you could even draft the grant for the district and ask them just to review and submit it).

Sorry, I know that's a lot to take in. Just want to encourage you that there are a lot of options out there. All hope is not lost. You have been doing the best for your daughter so far, but it is very, very common for parents to get burned out... even when their special needs child is in school during the day and in enrichment classes/special rec in early evening. I don't know how you've been managing so long, but God bless you for giving so much to your child. It's perfectly normal to have discipline/behavioral mod work most, but not all of the time. That doesn't mean it's not successful. Sometimes it can work for a while even, and the children regress or relapse. Consistency and keeping to a schedule are key. And there is no shame in asking for help with that.

Frances,  thank you for all the ideas.  I'll look into them as I have the time and energy.  I'll make a list and have my husband help me.  When I get depressed I'm really bad about follow-thru. 

Sounds like any student would be lucky to have you as a teacher.  It's especially true for my daughter that the teacher can make all the difference.  If she bonds to that teacher, she could go to that school forever.  But how on earth would I find that teacher?  (Just a rhetorical question.)  Plus, the teacher changes with each grade. 

Anyway, I do appreciate your detailed response and the warm welcome.  Just posting helped me feel better...I just took a shower, the first one in, well, let's just say a while. 

How about an afternoon intense exercise workout of some sort. Gyms are only $20.00 a month...or perhaps jogging or trampoline...something your child enjoys doing outside with fresh air. She could channel that immense energy into physicality. Also what about a recreational sport for kids her age...softball, track, soccer?

I know you said it was a rhetorical question, but I'll answer it anyways. ;)
Go to the school & ask to meet with the teachers. The school really should offer that to you as a parent, but it rarely happens. Be insistent. Don't get rude or anything, but just let them know that you really want to meet with the teacher to help your daughter prepare to re-enter school. If you see that there are things the teacher is doing that could cause problems for your child, mention it to the teacher & see if she is receptive to making modifications. If she isn't, ask to meet with another teacher.
For all that's said against teachers, there truly are wonderful, caring individuals out there. Finding someone who will be GREAT for your daughter this year can mean that next year she will be able to survive with a mediocre teacher (though hopefully that doesn't happen, I realize there are no guarantees). A caring, qualified teacher will work with your daughter to help her not just learn content, but also learn strategies to self-soothe and function in an environment that is slightly less ideal. As with anything, there are risks -- but the benefit of having a great teacher, being able to make friends, developing strategies & getting additional high-level feedback about managing her disability are typically direction-changing, if not life-changing.
Your daughter has a lot going on & any advantage you can give her, even if only for a year, can mean a lot for her (and you). I have seen the progress that a child can make in a year. Even in as little as 3 months, I saw a child with severe PDD change from screaming any time a person or thing touched him, to being comfortable enough to occasionally give hugs to his parents & favorite teachers, and to be okay with someone accidentally brushing up against him for a second or two. He learned to refocus & not have a complete breakdown, and that was in only 3 months. He had a mediocre teacher the next school year & b/c of what he learned with my co-teacher and me, he survived... long enough to make it to the next grade level where he had a fantastic teacher who was a mentor to me. Behaviorally, I didn't even recognize the child by the end of that school year.
So my advice to you -- as it is to anyone with depression -- is to focus on today. Don't let your head get filled with regrets about yesterday or fears for tomorrow. Today is what really matters & today is where you can have the greatest impact.

((((hugs for Aviana))))

hang in there! :)