Hi, i had unprotected sex on my 10th day of menstrual cycle. i know it's not safe because my cycle lasts for 28 days. regular. never missed a period. then we had unprotected sex again on day 19 because i know it's safe. but i bled after intercourse. i thought it's already my period but it's not. it didn't push through. just a tinge of pinkish discharge for like minutes. could it be implantation bleeding? could i be pregnant? never had this experience before. been nauseaus lately as well. but im still thinking i could have my period anytime this week.