I think squeezing your cock so hard when you jack off is probably at least one reason for your issues. You're used to intense pressure on your cock when you get off, and although your cock is huge, a pussy just doesn't squeeze that hard. I would suggest cutting down on masturbating, especially during the day / the day before you know you're going to have sex. Also, try training yourself to still get off while not grabbing it quite as hard. This will be tough, avoiding what you know will feel the best, but remember how much you want to have a normal sex life.
Other thoughts:
Trying extra thin condoms could help, I had a friend in high school who couldn't come the first few times he fucked his gf. Just didn't feel anything on his dick really. Then he got some thinner condoms and the problem went away.
How strong is your connection/attraction to your partner? I know there's been a few times for me where I was questioning whether I was really just using someone for sex and it usually became harder to achieve a hard-on/orgasm when we would have sex. Feeling guilty or shameful about sex, even sub-consciously, makes very hard (well actual the opposite lol) to be completely engaged and enjoy it.
I also read an article recently that was describing a phenomenon where a lot of young guys are having similar difficulties as yours and it was attributed to watching too much porn basically. The theory was that because porn is so stimulating and diverse (you might see 20 different girls getting fucked in one jack-off session) that your standards for arousal become very high and a real life girl is almost boring in comparison. Do you not feel totally turned on when you try to have sex? If you think this might be the case maybe dirty talk and more extended foreplay could help, as well as cutting back on the amount of pornography you watch. Or maybe try watching just one video and really focusing on that girl. I don't really know if that would help but it kind of makes sense.
Anyways, best of luck to you, hope this helps in some way or another, or at least gets you thinking in the right direction.