Pap smear results.

Just got a call saying I need to go back in a year to have another Pap smear. She said results were mildly abnormal. I'm 21. As far as I'm aware, do not have HPV. I believe I was tested twice during pregnancy. How common is it to have false results? My mom has had cervical cancer. She was 32 was diagnosed with it. The nurse didn't give to much info, just said mildly abnormal. And that if I have any problems to come in and be seen.