During sexual arousal, many things are happening in the female body. With the male, the erection is obvious; with us, the changes are more subtle. Sexual arousal includes lubrication secreted through the vaginal walls. The vagina also "balloons." That is, as we become sexually excited the vagina deepens and widens making itself much larger than in the usual state.

In your case, it appears that you are taking him in before your body has readied itself. Upon entry, the underlying muscles are being stretched and, without sufficient lubrication, the skin would be "pulled in" and hurt until he pulls some lubrication from deeper inside you. The solution is to add some lubrication and you may as well use spermicidal jelly to add some protection as well as lube. If you are using latex condoms, they cause more fristion than polyurethane. Change to poly condoms.

As far as the depth, most of us have felt some distention on occasion but not regularly. This really indicates that, unless he has a monster penis, you are really not aroused and he is bumping your cervix - can be painful. In rare cases, agressive thrusting can actually bump an ovary and that really hurts.

Do not be so anxious and get yourself worked up more before taking him in.