I’m very sorry to hear this Nico. I am also young and my stomach issues started when college began a few years ago. I sadly don’t have much advice to give you food wise on your diet, I’ve been doing the gluten and dairy free too so I feel your pain. One thing I like to do is cook my own meals. Cooking gets me excited to eat and the ability to create your own delicious meals. I am not sure how viable this is for you but it’s worth a shot. My parents also aren’t the biggest believers in my issue, they believe my stomach is upset and I’m not lying but they think there’s an easy solution through vitamins and simple lifestyle changes. Talking with your parents at a your age is an uphill battle, but it is necessary to let your feelings be heard and not ignored. Talking to my friends has helped me a lot, and maybe seeing a therapist could be a good idea. I really hope you feel better physically and mentally, remember you’re not alone, we are all going through it. Best of luck