Questioning Sexuality

Hi, I would like to know if this is normal or maybe I'm not heterosexual or something idk I'm very confused.

I'm 21 and I've been in a relationship with my boyfriend for almost 2 years. We are deeply in love and spend as much time as we can together, despite being long distance. I miss him every day. When we are together the sex is amazing and he knows exactly how I like it.

However, I still sometimes feel attracted to women or would like to have sex with someone I see.. when I was 12, my older step-sister forced me into touching her and she would touch me even when I said no (it's very complicated). I also had a secret fling with a girl when I was 13 and we used to meet in secret and kiss and touch each other. I decided then that i didn't like it and id only done it to see if it was any different from my step-sister. When I was 14, I was raped by my then boyfriend and it took me a while to want to have sex with boys which I thought was because I might be a lesbian and I was worried that people might reject me. Anyways, since then I've only kissed a couple of girls (strangers and close friends) when I was drunk and i sometimes wished that I could do more with them to see what it was like.

Does anyone else ever feel like this? I feel like I can't talk to anyone about it and I'm worried of hurting my boyfriend. I'm also worried that the stuff I am feeling is because of what my sister did when I was younger..

P.S I really don't want to offend anyone, I'm not used to talking about these things so please forgive me if I said something wrong.