Finally feel desire for the first time in my life! I have a mental block about it though, any tips?

I never felt any sexual desire to top or bottom previously but I think the bottom in me is being born now! I experimented and masturbated anally once and all of a sudden I know have a constant feeling in my prostate. It feels good. It's accompanied with a desire to have something put in it. I even for the first time get hard when fantasizing! It's great and I hope I can explore this when I grow older and have a boyfriend.My only main concern is that I feel kind of... mental block-y about it at the same time. I feel uncomfortable and ashamed of it because I feel no other desires than this. I never have had a desire to top or fantasizes about anything in between. Its almost like I can't accept I'm a bottom. I think it's because I associate bottoming with being submissive and I am the farthest thing from submissive, but that's just a theory. I'm also uncomfortable that I have no desire to top, because I really should and I really want to try it, but the desire just simply isn't there. No urge at all to do it, unlike this constant good feeling in my prostate.I'm 16, a virgin, and while I'm trying my hardest and getting some guys' numbers, they always turn out to be straight. In other words, I've never had a boyfriend. I don't have anyone else to explore my desires with, but I do want to explore my desires anyway and hopefully cure my mental block.Tl;dr - what do your urges to bottom feel like? - what do your urges to top feel like? - how can I explore my desires by myself while I have no boyfriend?