I think it's a pretty common occurrence! When I was female, I was sure I was a lesbian, but now I know that I'm more a gay man. The hardest part was explaining to my family, who I had come out to as a lesbian in high school, why suddenly I was bringing home men, without anyone thinking I was just going through a "phase" earlier!
My change in attractions is actually what led me to realize that I could love men while being a man, too!
Sexuality is fluid, I think, and you may find that your preferences change as you get older or as your body becomes what you know it's supposed to be. It seems like you know that it's all okay, so good luck, and take pride in loving and being attracted to whomever you like!