I know I'm replying to your post late, but hopefully you will see this response. My DS has FPIEs - he is currently 3 years old. He originally had FPIEs to milk, bananas and rice. His worst reactions were always to rice and that is the reaction that is sticking around the longest. He outgrew milk at 12 months, and bananas around the same time. His last exposure to rice was about three months before his 2nd birthday, and while his reactions have gotten milder (vomiting about 3 hours (used to be 2 hours) after ingestion, but only a few times and never to shock) he still reacts to rice.
I get your frustration with Doctors. None of my Drs. ever diagnosed him, they kept brushing me off, since my DS was growing and thriving despite this issue. I finally got online and did my own research and found FPIEs. After I had him tested for a rice allergy at 9 months that came back negative, and gave him some puffs with rice after that test yet again, that of course caused a reaction, I brought this up to the allergist who agreed that this is most likely FPIEs. I never got a course of action or game plan from the Drs on how to best help him outgrow this, but from doing my own research online, it seems the best course of action is to keep your child reaction free for as long as possible. We've been reaction free for 15 months now - i plan to get to the 2 year mark and reevaluate. Ideally, I hope to challenge my DS when he gets to an age where he can tell me what types of symptoms he's experiencing (tummy ache, nausea, etc) before I expose him to rice again.
I know it's scary, but you can slowly start taking your litte one out to restaurants with you, just be aware of hidden sources of rice flour. My list to look out for: french fries, chicken nuggets, sprinkles. Whenever possible, I ask for fruit or a vegetable instead of fries, look up the ingredients online if posted, or just talk to the restaurant manager. People are super understanding of allergies and food sensitivities these days and will be more than happy to accomodate!
Good luck on your journey. It really DOES get easier!