Questioning

I don’t know how to start this off but I’m 16, have a boyfriend and I think I’m a lesbian, I need help. I have had sex with a guy before but I completely regret it, not actually the action but what gender it was with, when ever I think about doing sexual things with guys my stomach drops and I can’t get myself to do it, my boyfriend wants to and I don’t blame him for that, I love him but I can’t get myself to actually do anything but kiss. I talk to my friends about it and they always say “don’t worry that’s happened to me too, he’s probably just not the one” but I don’t think that’s the case. I’ve questioned about being asexual because I’ve always thought sex was meant to be a guy and a girl and I don’t want that, I’ve been recently thinking about girls and I don’t get that feeling. I’m really overwhelmed right now and I don’t know what to do and on here is the only place that I can express that. One of my friends had asked me if I think that I like girls but I completely shut it down because I’m scared of judgment, a lot of my friends had said bad things about the girls who had came out and I’m scared that they will think the same. I feel horrible about myself and I don’t want to hurt my boyfriend but I can’t change the way I feel inside, I’m really scared.