You're right! - when you are allergic to something that can cause you a lack of vitamins and minerals, that's not a very healthy thing!
Do you take a multivitamin? There are many on the market that you could try. And you do mention that you do have a few fruits and veggies that you can still eat? So between the two, I think you are off to a healthy start!
One other suggestion - there are also drinks that are available that can supplement vitamins and minerals, like Ensure and Boost, just to name a couple. You might want to try that.
Let me know how you are doing and keep up the research!! That's absolutely wonderful to see someone at your age trying to find help like that - that's what I do, too!