Is it normal to become gay over time?

Hey all. All of my life I've been in hetrosexual relationships. The problem really started about a year ago, I began to feel more feminine in myself and I started to realise I was getting obsessed with cocks. I explored my feelings slowly in myself as more of an experiment really than anything else. I had no plans to act on them. But I have become a bit of a secret crossdresser and own a small subset of female clothing. I took some pics of me dressing and shared them with some guys. At first it was really all just a bit of fun, to see what would happen. I couldn't help it, I thought I looked better than I expected dressed and I wanted to know what other men thought of the pics out of curiosity and... although I was acting in fantasy, I guess that a part of me wanted to feel wanted. But I started to like the compliments and the naughty things men said they wanted to do to me. I've become a little addicted to chasing those feelings. Now I'm starting to wonder what is happening to me. Am I turning myself gay... somehow. I've tried to stop myself, but I just can't help my submissive urges towards older men from taking over on a daily basis. Like today I've woken up with it on my mind. What has really brought this to my attention is that I am now struggling to get an erection for females even though I didn't have any trouble in past, but when I think about a recent older man that I have been chatting to, and his (frankly gorgeous) huge cock and balls, I get hard instantly knowing that he wants me at the weekend. Since he asked me to meet him, I've been daydreaming about his pics in my uni lectures, and I regularly get butterflies in my stomach. I feel like I am losing control and becoming obsessive. Is this... well... I'm not sure about normal. Lol. But... can anyone else relate or please explain what is happening to me? Thank you.