Could I be pregnant? how to find out ?

Patient: Hello, so I had protected sex a few weeks back I’m also on Diane, my period was a week late though and then a week after it was over I started bleeding again while on Diane, I’m starting to get paranoid and was wondering if I should take a lab pregnancy test but how accurate would that be if I can still see a few spots of blood during the day.what could be causing this? What should I do ?This is my second month on Diane. And I have polysystic ovary. And getting pregnant is not an option!