Bottom

So before I had my very first sex I was always getting aroused imagining being the bottom and generally Al the stuff a bottom does in sex. But when I did for the first time and the second one I felt pain fear anxiety and not much pleasure out of it..I would to try top but it doesn't make me horny enough..do you think it's just a typical think because it's just the beginning and I will get pleasure out of it later or is it something else?Thank you☺