Tired

Hi, this is my first time ever posting so bear with me. I (16 F) just got diagnosed with POTS in October, I spent 8 days in the hospital while they tried to figure out what was wrong. I know that POTS is way more common in teen girls but I feel like utter crap. I get flare ups all the time for example I was in the ER last night because my BP was 77\40 and I felt like I was under twilight anesthesia. And I'm trying my best to drink all my water I'm supposed to have 2 1\2 liters a day and 10-12 grams of salt which right now feels impossible. I just feel so defeated because no matter what I do I get dizziness, nausea, palpitations, migraines and more and I don't know what to do I'm on the verge of a mental breakdown literally everyday and I feel like it's not getting better. Can I get some advice please if possible? Thank you.