I thought I knew I didn't know

I realized something last night, as I had a feverent argument with the bf. I'm suppressing something and it's slowly destroying me and the relationships around me. The things that matter most.
Earlier in my blogging, I believe, as I was going through a progressive state of downfall; I spoke about why I started doing any of this blogging at all. Aside from chronically my crazy life like never before.. I was searching for what kept me going back to that pitifull state of depression. Why I'd take small steps forward then regress huge steps back. What keeps pulling me back there?? Why can't I get past this thing??
It's because I don't know what it is... So I can't fight it.. I don't know the triggers or the harm that it did.. or has done.. or will do.
Earlier (in the blog), I talked about the book Sexology by Carly Milne. It was the reason why I knew I had to do something about my life.. because something was holding me back.
So here's the situation as blunt as I can make it:
It seems that I have trouble having sex with L. But I don't know why. Honestly, I like sex (I think), and I love him. He's my bf.. why wouldn't I want to have sex with him?? It only makes sense.. but I seem to constantly push him away. I'm always scared of having sex with him and it takes a lot (from me) to get me to want to have sex with him.. and then to actually have sex with him. Sometimes I want to.. but I can't do the act. I don't know why.
He's expressed that he thinks it's because I'd rather be with a girl than him and although I am bisexual that's definitely not it.
But what hurt me the most was how hurt he was by pushing him away.. he felt like he was forcing me sometimes.. and frankly most of the time it feels that way to me. But that's not the case... I know it's not. (And please trust that I'm being truthfully in this. If I say no.. it's no and he walks away.)
But I'm left asking myself why I feel that way?? I then realized something. I remembered when I discovered that my odd issues with sex and sexuality stemed from something that happened a long time ago. Something that I buried far far away, and now it's leaking out. I realized that this event that I can't remember is rearing it's ugly head and I can't ignore it any longer. So here I am with the realization.. just when you think it's ok to not know, you realize that you no longer have power or control. Not knowing hurts far worse. Because you can't protect yourself or others and you can't help yourself or ask for help from others.. I wish I knew what happened so I can put a stop to this. I've decided to seek professional help, or this will no doubt effect my baby. I checked out this site that helps women with pre and post partum depression. Even though my problems derive from something way before the baby, it's taking it toll now.. at the worse possible time. I sent them a message. Something just short of begging for help. Hopefully I get a call or email within the next few days. I don't know how much longer I can deal.

post/prepartum resource center