Yes in fact I did have problems because of size. First of all, I am sure that guys with smaller penises get better oral sex. Women can't fit much of a larger one into their mouths.
One time, while having sex with this lady while trying to enter her, it was really tight. I was taking my time and she was making a face like it hurt her. At several times it actually appeared she was crying. I tried to stop several times, to withdrawl from her but she pulled me back into her. I felt bad but when it was over she appeared to be crying and laughing at the same time (that's the best I can describe it). Afterwards she said that she really enjoyed it but I was a little uncomfortable because I thought I was hurting her.
Another things is condoms don't fit well. They usually only go partway up the shaft and tend to work their way off as you go.
Sorry this sounds like a p 0 r n novel but I didn't know how else to say it.