[19M] Gay but likes breasts???

Hi and im James, a 19 year old gay man who’s been sure of his sexuality since age 12. I’ve never really noticed or checked out at a woman’s breasts before but for some reason I couldn’t stop looking at this girl in the gym this morning. She was wearing this tight tank top and her breasts were bouncing around in them like crazy and for some reason I caught myself really turned on by them? Can someone please tell me this is normal. I have never had interest in any woman before in my life and had never even thought of myself possibly being bi. Please help lol