Hello~I am so sorry you are suffering like this. I am going to agree with the others, please get that test done, they will no doubt give you something so you don't gag or throw up. With your symptoms, it is a good idea to have as many tests done as possible to get to the reason of the awful feelings you are having.
I hate to say it, but stress and anxiety was the first thing that came to my mind as I read this, school brings lots of stress, even if you are not aware of it. The stomach is very sensitive to any type of stress, good or bad, I know I get a tummy if someone looks at me wrong.
So, have the tests, ask what the abnormal blood results were, it is your right as a patient, and in the meantime, drink some herbal teas, mint, ginger and chamomile are great for tummy issues and they are relaxing as well.
Let us know how you are doing and how the tests went. :-)
As Barb135 said you should go and get checked. All test are more beneficial to you then harmful. In addition I know how hard it is to hear a doctor place your problems on stress and physiological issues. Mine often do that to me, because BH conditions run strong in my family. I am sorry they did that to you, and you would know best...just make sure you are not in denial because many health issues can be stress related.
We can sit here and recommend or tell you what we think it is over and over again. But with how young you are, I dont think that is really helpful. You should go do the testing recommended and follow up with your doctors. As you get results you can share them and we will all be here to share what we have found to go with those results, but even then you need a doctor's help.
Two things come to mind for me. First, blood sugar. This can actually make us nauseated when it is low. And second, stress and anxiety. Issues like this are some of the biggest things school age kids report when they are anxious. I know that you say it is not related to stress and a psychological issue. So, sorry to bring that up again but it is definitely something a lot of kids in school report. I had an ulcer as a preteen that was an ulcer in my intestines, called a duodenal ulcer. This also caused me to feel quite nauseated and often after I ate. It was found after an endoscopy (camera down throat looking at stomach and intestines). I was sick for months, literally and lost a good deal of weight. I too had the suggestion made that it was psychological. Anyway, they treated the ulcer with a substance I drank and it healed within a week after several months of plaguing me. I would see another GI doctor and start some testing.
What 3 elements of your blood work weren't normal?
There could be numerous causes for your nausea and gagging feeling. You should go ahead and keep the appointment for the gastroscopy because that could tell them what your problem is. The chances of your throwing up or gagging are pretty slim because they will give you anesthesia to relax you/put you to sleep. They are trained to deal with such possibilities and since it could help with a diagnosis, it's to your benefit to follow through.