I've been on the yasmin birth control pill for a little over a month. I have had problems with cysts and I currently have a large one on my left ovary which my doctor is aware of. I noticed that after I had sex a few days ago, I have been feeling on and off just a little nausea. I was told that the cyst can cause nausea but of course my mind runs wild about am i pregnant??

My only "symptoms" are that I have little nausea but it's enough for me to notice and be worried about. And I am a little bloated.
It makes no sense in my mind because how can I be pregnant after being on the pill for over a month?

Any advice??? I'm worried.