Can't cum with girlfriend

Hi,

I have been with my current for just over 5 months now and to get to the straight to the point I can't seem to cum when i am with her,

When we started going out both of us virgins but around 1 month in we started having sex, the first few times it hurt as normal (i think) but now she doesnt experience any pain. However I do get a pain/discomfort sometimes during, as my foreskin gets pulled back and it becomes uncomfortable, it has bled once during sex and we just stopped, but not recently. Also there is no pain during sex if she is really wet, we tried water based lube but it is uncomfortable for her, it stings her as does the lube on Durex condoms. It also sometimes hurts when she is giving me a handjob and pulling it back too far.

I used to masturbate about once a day but ever since being with her I have turned that down to about once every 3-4 days. Whilst masturbating I have no problem at all cumming, normally takes around 5 minutes if I am going for it.

I admit that I am a bit of a worrier always thinking about if people can hear us and whether of not I am doing everything right. I just do not want to disappoint her so I keep thinking too much.

Could this all be down to stressing out? If so how do I overcome it?

Any advice or personal success stories would be greatly appreciated,

Please help......