Suggest Treatment For Irregular Period

Hey Doctor. I am just way too tense n stressed up about this matter. I have a problem of irregular periods for which i was prescribed Lynoral 0.05 mg from 5th day for 20 days, twice a day and meprate from 16th day for 10 days, twice a day. I started these only from the present cycle of mind. But on the 7th day, when i was still having brownish discharge, i had an interaction with my boyfriend. He rubbed the shaft of his penis around my clitoris for the 1st 10 seconds, but never ever penetrated inside. I am not sure of precum entering. but i cleant it right then. and we stopped. I am still a virgin and he has never tried to enter my vagina. on the 8th day too, i has a brownish discharge (which is very common, i have brown discharhge till 9th or 10th day). I have a few side effects like tender breats initially when taking meprate, but now its gone. I have never missed a tablet. but its the 5th day after stopping merprate, and i still didnt have my periods. Also, i took a pregnancy test today, and it was negative. I am still worried. Could i be pregnant?