Asexual? Idk my sexuality please help.

I think I might be asexual but I don't really know. I kind of assumed I was straight and am currently dating my first boyfriend. We connect emotionally.... But physically, it lacks on my side. When we make out, I honestly get no pleasure from it whatsoever. He's the only guy I've kissed, so at first I thought maybe I was a bad kisser? But we have a good rhythm and its not like we bump teeth or anything. He strokes my face, grabs my waist-- all things that my friends say drive them crazy-- but I honestly get no feelings from that. So last night things got kind of heated and we basically started grinding. He had a major boner... And I... Felt nothing. Why am I not sexually attracted to my boyfriend? I even considered the fact I could just be lesbian... But I'm not really attracted to anyone to be honest. I just don't know what's wrong with me. How do I find out if I'm truly asexual or not???