That's very rude of people to say they can't invite because you're vegan. Are they worried that you'll make them cooking something else just for you?
When you get invited, just let them know that you're vegan now and tell them not to worry about you being an inconvenience to them that you'll bring your own food. If they still don't want to invite you, you should ask yourself if you want these people in your life.
When you get invited, just let them know that you're vegan now and tell them not to worry about you being an inconvenience to them that you'll bring your own food. If they still don't want to invite you, you should ask yourself if you want these people in your life.