Bfs family forcing me to eat food

So heres the deal I have been a vegetarian for 10 years. I get all my nutrients/vitamins/protein etc I'm very healthy lots of fruits/veggies beans. I have been with my bf for 3 years. His parents have always had an issue with what i eat and have made rude comments I usually rub them of but the other night they were basically listing foods at the table that his mom said she will force me to eat! I was like seriously I'm fine eating a salad and pasta when I go over there house. I eat any vegetables and there are so many vegetarian food options! I'm allergic to many fish, shrimp and lobster. His mom goes you can eat crab and I said no I don't want to risk it since I have severe allergic reactions to shrimp and lobster. I'm frigin 22 I shouldn't be forced to eat food when I go over out with them or to there house. How do I stand up for myself? My bf was like they want to help me but I really have no issues I'm happy and healthy!! What would you do?