I told my friends not to order non-vegetarian foods at my birthday dinner.
Why would you give orders as to what people can order?
My friends are kind of notorious for not taking my orders seriously in food.
Even on your birthday, you shouldn't force your friends to eat exactly like you do. You should be respectful of everyone's preferences or else people will start to think you're weird and stay away from you.
Fuck them.
If you care about your friends you should let them order what they want. They are spending their money, so you should let them pick out something they like. Don't tell your friends what to do or they won't want to hang out with you again.