Birth control!!!

I really need help choosing a birth control pill. This will be my first time using one ever in life. I have cancers so I cannot use IUD's. Any suggestions on the best options? I want it to work so I can begin treating w/o the risk of getting pregnant again and my OBGYN keeps asking me what I want to use. I'm easy to get pregnant so I need something that really works with few side effects. All responses are appreciated!😌