This is probably a kind of strange question but here goes. Yesterday I was about to have sex with my gf, and it just plain wouldnt fit. The other day we had sex with her on top that worked.. i wanted to try from behind yesterday and she was just too tight. i was seriously wondering if I was going to be hurting her so we just ended up doing other stuff. Im not 'huge' if anything id say im average sized, but she hasnt had sex in like 8 months. Do I just need some lube, or am I just being too cautious or what?