HI!
I ALWAYS recommend a pregnancy test, just in case. It does not sound like you are pregnant though. It may be that your cycles are just a little irregular lately. One concern I have though, is that I have seen cervical biopsies cause scarring of the cervix which basically closes it and won't allow the period blood to drain out.
If you keep missing your period, and your tests are negative, I would recommend having your cervix checked and possibly dilated open again.
Good luck!
Dr B
Yes! I believe you still could be pregnant go to the doctor and have them do a blood test! If you dont have insurance or cannot afford a visit go to your local health department and they will give you a urine test and then if it is negative they will see you in two weeks to go from there! Are you trying to get pregnant?