Hi Jasmine --
So sorry to read about all you're going through! High school is difficult enough without having to deal with terrible health issues.
I want to give you something totally different to consider, to talk over with your parents, and your doctor. You've described some serious symptoms, and your doctor(s) haven't addressed this. I'm not surprised...my experience with GI doctors has been very poor, generally speaking, and I've been to eight.
You need to have your blood tested for the celiac marker, but even if that comes up negative, it's possible you could still be suffering from something called non-celiac gluten sensitivity. If this is the case, the only way to diagnose it is on a trial gluten-free diet, and then "challenge" the diet after a few weeks to see if the challenge produces symptoms (assuming that you are better at that time). This type of food intolerance can be host to all sorts of non-specific symptoms, including asthma, and even GERD.
There is also another potential antagonist, with a similar molecule to gluten/gliadin...and that's casein. Often, people with this sensitivity can have intolerances to both. There are specific blood tests for these intolerances, but the antibodies won't be apparent in significant numbers unless you are ingesting foods containing the proteins in question. In other words, if you experiment with the diet on your own, you can't be tested accurately while on the diet.
Unlike food allergies, like with peanuts or kiwis, for example, food intolerances are subtle, and insidious. An allergy will produce symptoms immediately, while an intolerance can take hours, or even days to appear. This makes diagnosing it all the more difficult. In addition, a special diet can take days or weeks to produce noticeable results, not only because it may take time for the irritating molecules to leave your system, but also for you to heal to the point that your immune system is no longer attacking various points. This point is important to understand, because it's possible you may not notice significant improvement until a month has passed. Perhaps you may feel better after a few days, but a diagnostic diet such as this should last at least four weeks.
I don't mean to increase your anxiety, but at this point, it appears as if you're still chasing symptoms and not making any progress. Hopefully, thinking "outside the box" will bring you to a more comfortable place. I'm not suggesting that this is the answer for you, but it may be something to consider.