Can you get your allergy test information or some medical document from your previous doctor that proves you are allergic? If not, then the only other option is to contact the National Food Allergy group and ask them to help you out. Your doctor needs to be told by people with clout that you can be allergic to anything and that people have gotten violently ill due to doctors refusing to believe that "specific rare food allergy can't be found by me". Besides, we all know that skin tests and blood tests are not always very accurate.

For the family - I would find and show them pictures of all the people who died from food allergies. I would also use any resource you can get from the Food allergy group. I can't remember what they officially call themselves. Sorry!

For you - I would clean the kitchen and cook my own food before they cook their food. I would also make a point of marking my leftovers in such a way, that I'll know if someone opened it or contaminated it. Getting your own fridgerator (mini, perhaps) in your room, might also help. My dad was most unhelpful with my own food allergies. He was in extreme denial. My sister told me to say, "I'm so glad you and I are on the same page because my not having food allergies are all in your head!" He did come around and finally realized that I really am allergic!

What we don't want to happen - you to actually have a reaction and have to be rushed to hospital. However, this will make them see first hand how selfish they were. I can't live with my dad. I react by smell to poultry.
Best Wishes!

As you posted 3 months ago, I sure hope by now you have seen the allergist and have your EpiPens (or generic equivalent). I don’t tolerate diphenhydramine (Benadryl) well either and save that for life-threatening situations, but cetirizine (Zyrtec) works on a daily basis.

I had to describe my reaction to oranges to my doctor before he believed me that I was allergic to citrus fruits, citrus anything! He rolled his eyes st me about prescribing an epi pen, but did so because I told him I would feel better about it. I still struggle to be sent to the allergy clinic. Try to find a doctor with a low visit cost. Otherwise you're left with calling emergency services to get the epi back. I have found eating plain rice, plain piece of bread, or unsalted crackers help, and drinking something ice cold.