How can I control my anxiety on dates?

I recently met a guy on Grindr and he’s really nice, polite and kind. The problem is that I have really bad anxiety and I don’t even know what sexuality I am since I’ve never been with anyone.I met up with him after we talked for about a week and we went for a walk around. After about 15 minutes in I was physically sick which made me even more worried (he was really nice about it and told me that it was okay and even helped me clean up).My question is simple, how can I avoid the same thing happening again?