She doesn't seem into sex much

Hi all. My girlfriend of over 2 years doesn't seem into sex much. This has always been this way. She never ever once has initiated sex with me, or initiated a change of position, or anything at all sexual with me. I have to do all the work. Besides some slightly heavier breathing when we do it, she is mostly silent. She never masturbates or even plays with herself. I just feel that she is not very sexual and adventurous at all, and she never talks about sex. She doesn't seem too phased by foreplay and I just get the feeling she is only doing it all for me, just waiting for it to all be over and done with. It really makes the man feel down when he knows he can't truly please the woman and have great sex, only just sex.

She does seem to like sex once we get into it, but no where near the scale of other women I have been with. It is fustrating when it is the time of the month where she doesn't want to, because she won't say anything until we begin the foreplay! She seems to have too many inhibitions. How can I release these from her? She also has a lot of clitoral hood and labia loose skin more than I have seen before on a woman, and she seems very overly sensitive.

We have a daughter together, she fell preg only a couple months into our dating, so I have not felt inclined to leave. I feel I am in a potentially dangerous situation here because she doesn't make me feel truly wanted, even though she says she loves me, if sexual offers from other women come on down the track, I cannot help how I currently feel in the relationship and this may drive me to infedelity compared to if she was more sexual toward me and made me feel more exclusive.

I have tried bringing up the issue as carefully as possible with her many times, but she tries to avoid it by going all passive-aggressive on me. Iin?

Help!