Here is my husbands advice:
1. Male sure you are having sex on a harder surface, instead of a soft crappy mattress. This way you can control penetration and go deeper.
2. Are you using condoms? Sometimes they can desensitize the penis and you cannot feel the tightness.
3. Are you using medication? Sometimes meds can kill an erection or orgasm.
4. Finally, is the problem that you cannot feel youèr girlfriend? Is she tight or loose?