what am I?

Hi, I hope you guys can help me out. I am not sure if I am gay or straight. I am a male in my early 30’s and a virgin. I am unsure because I find girls attractive and am turned on by them. I am also attracted to guys, you know the muscular athletic type. Not sure if this is an envy sort of thing because I have always wanted to look like them but can never seem to get the motivation to do it. I have recently joined the YMCA to start swimming. Another factor is that when I jerk off I usually(95%) think about muscular guys, or small guys gaining lots of muscle, or fat. There is never anything sexual going on in these fantasies just growing big muscles, or fat, or already having muscles.
I am very lonely and really want to be in a relationship and can’t seem to talk to girls, or ask for a date. Never thought about dating guys, does not interest me. I did have a very confusing dream that I was going to have sex with some other guy, but I remember feeling very confused and had lots of mixed emotions about it, I woke up before anything happened.
I have been thinking about going to a therapist because I am so lonely and also feel depressed and just really need to understand all of these feeling. Thanks.