Suggest Treatment For Prolonged Period

I have just seen my GP because my current period has been going on for just short of a month, she is checking my blood count but also wants to do a pregnancy test surely bleeding like this (they are very heavy as well with clots daily) I cannot be pregnant. Ive had similar problems for the last 13 years and I am only 25, there was a question over me having PCOS because I have most signs except the cysts what do you think it could be thank you