First of all- start standing up slowly when you do and pace yourself once up. I can get dizzy standing up too fast & that can trigger anxiety.
Secondly, I used .25 Xanax and took it up to 3x/day when things were rough. That's the tiniest dosage & you can take 2 at a time & see if that helps. Honestly, most ppl I know take .50 or higher per dosage. .25 worked for me but you bet I would have taken more if it wasn't taking the edge off. My psychiatrist even gave me permission to do so.
Finally, per the breathing exercises, I got the same way at first too. So instead of intentionally setting a time to do them (too much pressure in the beginning!), I practiced randomly through the day. You could go buy a harmonica. It's silly but fun & absolutely increases breathing & helps exercise those muscles. They recommend ppl with asthma to use them! I bought one lol. I sound ridiculous & my dogs run and hide but it's kinda fun too
Also, have you seen an ENT to check you out? Sometimes benign and simple polyps can cause obstruction & cause you to feel stuffed up which sounds like a trigger for your anxiety. Do you have allergies? Maybe an allergy pill might be considered.
One day at a time. You're at ground zero starting out and you are going to be fine.
I'm sorry but I can't remember if you're in therapy? It's a good time to think about
going if you haven't. What's your daily schedule like? A schedule is so important.
Sending you peace, healing and courage!
Lisa