Questioning sexuality?

I’m 15 in high school and recently I’ve been questioning my sexuality. Every time someone has asked me I’ve always said straight because I’ve always shrugged off the little crushes I’ve had in girls as hormones since they never lasted long at all. Now I have a boyfriend but I think I have a crush on a girl. I’ve been feeling like this for about a month. I feel bad because if I am bi I wouldn’t know how to come out because I don’t want my friends to think that I’m just saying that because all of my other friends are gay. And I don’t want my bf to think that I want to leave him for someone else or that I want to cheat on him or something. Please help.