What is happening to my body?

I'm 19, and when I was 16 I thought I was gay. Until I turn 18 I started having sexual feelings for girls. Now, I'm about to turn 20, and I'm strongly sexually attractive for girls; furthermore, I'm thinking of having a girlfriend, too. On the other hand, I was curious about gay sex, but never encounter it; and this was when I was 16-17 year-old. I don't find gay sex exciting, and find it gross, since it's were waste goes; no offense to those who enjoy it.I am, though, attractive by the male body, and his face, if he is cute. So what is happening? Also, am I still going through puberty?