Anxiety and fear due to a scheduled endoscopy

Hello there I am 17f, like the title suggests I have an appointment for endoscopy soon and I'm really scared. I've had problems with my stomach for a while consisting of nausea, a need to throw up, dizziness, loss of appetite and overall stomach pain before, during and after any meal.

It all started happening a few years ago when I starved myself and developed an eating disorder Ever since I've experienced all these symptoms. After some time my eating habits became healthier, but those symptoms stayed. I haven't went to my doctor instantly, but after a few years I decided to see what's going on since the symptoms just worsened over time.

Also last year I was prescribed with some antidepressants and for some reason my nausea just became even worse, I couldn't go a day without a need to throw up and a acid like feeling in my mouth. I lost a lot of weight because of that.

My first visit to gastroenterologist was around 3 months ago, where I just got prescribed some strong medicine that was supposed to ease up my symptoms, but It didn't. I still never got a diagnosis and I was bothered by that, I was afraid it could be something serious. The staff wasn't really interested in helping me out so I complained and got scheduled for a endoscopy.

I've seen some pictures and videos of the procedure but it seems so eerie to me, like something out of the horror movie. I should also mention that my gag reflex is really prominent and gets triggered almost every time I eat or wash my teeth. I never went through anything similar and I'm worried since I don't know how it'll turn out.

Do you have any advice for me? Sorry for a long post I'm kinda stressed atm