What To Do For Cyst In The Ovary?

I am a 19 year old single girl. I was 17 when I discovered I had an endometriotic cystectomy. It was 10cm big in my left ovary. I got operated immediately and the cyst was removed. I was on Diane 35 till I stopped taking it in June 2011. Now, I have discovered that the cyst has developed in the left ovary again. Right now, it is 3cm. My doctor suggested me not to continue with Diane since it effects liver and I'm just a teenager. I need to take pills in a longer run. He tells me to take normal contraceptive pills. I'm confused as to what to do?
My blood test reports are normal. My FSH and LFT are normal too.