Yes we were using a condom but The condom was a tight on me which could be a problem, and that makes sense. Another question is I've been reading online about how porn desensitizes dopamine receptors in the brain and cause less arousal, hence weaker erections. On another site backing this info it says waiting 6-12 weeks without any stimulation will "reboot" your sensitivity and make for harder erections. Could this be something I can be hopeful for??
I wouldn't think the condom would make much difference but yes you are right about the porn can cause problems as I have said many times on this site, you can always try laying off porn and masturbation and see if that helps, also as I said there are many factors why your finding penetration difficult and the two main reasons are because your larger than average and your girlfriend being a virgin and very tight.
Try to work on her more with your fingers first slipping one inside and slowly working up to two so it stretches her vagina a bit that way make sure your fingers are wet by sucking them and that she is really yet before you try.
Rather than trying to have intercourse and failing and her thinking something is wrong with her try bringing her to orgasm through finger stimulation and oral I'm sure she will enjoy that
How tight was it most condoms should fit a wide range of penises. What make and brand of condom did you use? And I would somewhat agree with watching prob or masturbating often somewhat dulls our sex drive because you build a new idea of what is ideal or sexy and if your gf doesn't exactly match it it can have some affect on how aroused you are. In would refrain from masturbating or watching porn for at least 4-7days and see what happens