The intimate part of my relationship is messing with my head

I want to apologize in advance because I may be rambling and not make much sense.
I'm a person who likes to know things but I just have so many questions and no answers, and it makes me nervous. I just don't get it, you know. If I reread some of my old posts I'd read that I more or less don't mind sex with my boyfriend but when I compare it to how I feel about it now I don't understand how much it could changed over the span of not even a year. How's that even possible?
He was away for a few days and when we met yesterday he was soft and loving and touchy and wanted to do it but I had this "ugh, the weather's so hot, I don't wanna get even more sweaty" kind of thought. I did it though, and surprisingly climaxed but felt almost guilty about it afterwards, like I don't deserve it because I'm such a bad girlfriend who doesn't enjoy sex with her boyfriend and stuff.
I don't know if I'm sexually attracted to him or if I ever was. I recognize if I'm sexually attracted to new people but with him I'm not so sure. I definitely fell in love with his personality first. After I realized that I love him I became eager to sleep with him and really curious about it and, even though my first was like "I dunno what all the fuss is about", I spent many years wanting to have sex with him even though it wasn't giving me the sexual release.
It seems like the momentum just stopped for some reason. I don't know if it's because I somewhat fell out of love with him (I still care about him a lot though), or because I feel I'd rather be with a woman. I just keep over analyzing and over thinking everything he does and everything I do when we are together and it gets exhausting. I fear that I wake up tomorrow and realize that I "lost the ability to sleep with him completely". I feel like I'm gay but on the other hand I feel like I need some more confirmation, preferably a real experience with a woman to be really sure. Ugh.
I decided to write him a letter because I'd be probably not able to speak about it but not before my exam is over. But I feel so not ready to discuss that with him.
Haha, I just realized there's no real question in my post... :rolle:

 

Thanks, guys.
@Choirboy I think you're right. It really seems that the more I'm accepting myself the less interest in sex with him I have. To tell the truth, I try to avoid it the best I can. The worst are the thoughts I have while doing it. When I think about it I haven't had straight fantasies for a decade, before I acknowledged that being gay is an option I'd had no fantasies at all, since then it's just women.

@LostMyself I read your last post and I also have certain things that I feel really uncomfortable about but the truth is that I think about them as rules. Haha. I really don't fancy when he's touching me down there for example. I always bear 10 seconds tops, then start doing something to him instead so as a result I seem to be a perfect sex craving girlfriend. Funny thing is that I'm really good at pleasuring him but I myself don't get much out of it.

 

Thank you, guys. Yes, that's exactly how I feel. I want to make him happy, and not to make him suspicious that something's been going on because I'm not ready to talk about it yet. Physically it's just a routine, a mechanical thing, mentally I'm not truly present. I have that inner dialogue that I should enjoy it and how I'm gonna enjoy it but it always turns out to be just a wishful thinking.
I thought that I accepted myself already but I still catch myself bargaining from time to time. Like if I hooked up with a few women I'd be able to let off some steam and get back to "normal", you know. I know it's stupid, even funny how the mind is playing me. I know I'm gay but I don't know I'm gay at the same time if you know what I mean. I think that not accepting myself fully is holding me back from telling him right away. :eusa_doh:

 

@stella99 @HTBO @Sig @DancingGirl It helps a lot to know that I'm not alone in this. I also read your other posts/comments and found them inspiring. Thank you, girls (*hug*)

Since I've realized that I was attracted to women my desire to be with one grew in a way that's almost overwhelming sometimes. There are days when I feel like a ticking time-bomb, ready to blow. I try to stay away from alcohol, especially in a tempting environment, because I worry I'd do something stupid. Not that I didn't. *sigh*
A few months ago I even did a "research" (=watched lots of male gay porn) on how to pleasure a man better in order to learn some new "tricks" and "moves" I could use on my bf. It's probably ridiculous but I really felt like I need to compensate somehow for my lack of real enjoyment and the feeling of guilt. Moreover, I was thinking if I'm better I can make him cum faster so it gets over with in more short time. But the truth is that whatever I do the constant thinking and feeling of guilt is still present.
I know what I need to do, what the real lasting solution is but...

 

I think that's part of the reason too, the last years I love him more or less "only" as a best friend, and me having feelings for a girl and discovering my sexuality was probably just an accelerator to the whole process. The sex with him was never spontaneous for me, I never fancied certain activities and being touched at certain places, but I was so much in love and willing to do anything. Looking back, I fell for him in some kind of a demisexual way, I didn't have a crush on him and it took me years for the feelings to develop.