Periods and ovulation. Help please

Maybe this is a stupid question I don't know. Just looking for an answer. I have (PCOS) I was put on metformin to help regulate my cycles and to help me ovulate. I had very irregular periods like sometimes I couldn't stop bleeding or I just would have a period for months. For about 2 1/2 years now I am having regular periods. My cycle is about 20-21 days. It's like clock work. I stopped taking my metformin at the end of 2012. I don't know if I'm ovulating I don't take OPKS I'm not trying to get pregnant but my question is with me having a fairly regular 20-21 day cycle could I not be ovulating? Our birth control method is pull out but sometimes we don't care and just aren't careful but I have not ended up pregnant and we have been doing this for two years. What're your thoughts? Thanks