There are many possible reasons for having bleeding after sex at your age. perimenopause is probably not the issue, since you are a bit young for that, and because you've had normal periods until now. Perimenopause does not present itself with bleeding after sex.
Cervical CA, is also highly unlikely, as you paps were normal since the freezing, and it is very rare. Most likely cause is a polyp on your cervix
, or something else which may have irritated your cervix, or it could be a mild infection (not necessarily an std
), maybe a fibroid
, or other possible causes. With an exam by your doctor, he/she should be able to tell pretty easily what it is and how to treat it. It would be very difficult to tell without an exam.
I hope this helps, please let me know if you have any more questions.