Not all guys feel they are too small length wise. Besides if you get too long its just going to hurt her. Width is a nice thing to have (or so I have notice).

As for her...beleive it or not she may simply not feel comfortable with you. Even if she says it, Even more so if you are getting anoyed that you can't get her off.

Stop thinking like a guy where we can hump a tree and get off, women need to relax and work up to it.