Having some trouble with school?

Hi! As a little background, I'm a freshman in high school and I have hypochondria, emetephobia, GAD, and pure obsessional OCD. I've always been an honor roll student with a bunch of friends (Sorry if that sounds conceited, it doesn't seem to be the case anymore anyways :(). But recently, my anxiety has been severely spiked, possibly because of the change in schools (but it didn't even bother me for the first two months, I loved high school until the end of October) so I started an SSRI called Zoloft. All it did was worsen my symptoms and make me sick, so I went off it. But to get to the point, I've been having a lot of issues with school lately. Not only do I feel uncomfortable due to all the upperclassmen, which heightens my anxiety (especially because I think they all dislike me for some reason, and my friends are all really popular among the upperclassmen and I'm a bit more shy with upperclassmen than I am with my own grade, so that makes me a bit self-conscious and anxious, as I always used to be outgoing) I also highly dislike the fact that the high school is so large and seems like such a huge deal compared to middle school, and in result, my anxiety has been greatly heightened. It's been really tough for me to go to school lately, and I often get thoughts like "This is too much for me to handle"/"How much longer can I go to school for"/"What if I can't do this"/"School is too much for me, what if I have a breakdown and do something horrible like self harm"(As a sidenote, I've never self-harmed, I actually avoid it at all costs and I'm frightened of it, despite the fact that my OCD intrusive thoughts rotate around the topic of self harm) and I feel extreme pressure and apprehension whenever I think of school. Occasionally, I find myself not able to go to school and I have a complete panic attack in the morning, and my parents used to be extremely understanding about it, but they're (understandably) becoming increasingly irritated, and now they're threatening to place me in a special school for people with anxiety if I miss school one more time, which makes me even more anxious, even though they do everything they can to help me, including getting the best therapist possible and a 504 plan for school. I'm becoming overly concerned about school though, as my grades have dropped from mid 90's to high 70s and mid/high 80's, which is something that's never happened to me, but I've been missing so much class due to constant panic attacks in school (I either go to the nurse or school psychologist to take a break, which is too often a whole class) that my grades have been dropping. I've also recently become distant with the majority of my friends, and I feel alone for a first, as I always used to be hanging out with my friends all the time in middle and elementary school, but now I'm just too anxious to join them every time they hang out, especially if it's somewhere that makes me uncomfortable, like somewhere far from home. I guess you could say that I'm mildly terrified that my life is on a downhill spiral, as I feel like I've lost everything that used to make me happy, like my friends, my ability to leave the house constantly (I'm not home bound, but I don't go out as much as I used to), my grades, and my ability to play sports (I had to quit basketball, volleyball, and soccer due to extreme anxiety). I'm scared that I'll have a breakdown and won't be able to go to school anymore, and I constantly worry about which day I might finally break down and not be able to go to school anymore, as lame as that sounds. I'm also extremely worried that I won't be able to go to college. I've resolved myself to improving my life, and I've been pushing myself to go see my friends even when I don't want to, but I've been having to leave early from parties due to panic attacks and I'm just feeling super down, because I want to quit thinking negatively and make my high school experience as best as it can be.

I could use some advice, should I be worried about an impending breakdown? Is there anything I could do to make high school seem a little bit less of a deal? Thank you SO much to anyone who read my whole story!

(By the way, if it matters what I'm doing to try to lessen my anxiety issues, I just started CBT 2 weeks ago but I've been doing talk therapy since a very young age- I've had recognizable anxiety since Kindergarten- but the talk therapy never really helped. My parents have also requested a 504 plan for school, my parents and I have talked to all my teachers and they're super understanding, and I've recently purchased a bunch of books tailored to changing anxious thinking to positive thinking)

Hey, hang in there! Anticipating heading for a breakdown just encourages your anxiety to make it happen. Say positive things to yourself - especially when your brain seems to be rapid-firing on negatives. I do understand where you're coming from; I was diagnosed with an anxiety disorder when I was 5. High school is hard and anxiety doesn't make it easier. I continually tell myself "I can do hard things" and make a conscious effort to do the things that my anxiety is telling me not to do. I had to learn to not use my 504 plan as a crutch and not always leave class. You're stonger than your anxiety!