I have a sharp pain in my lower left abdomen/back. I also am a week late on my period. I am sexually active but am ALWAYS protected. I am just worried that I haven't gotten my period. Is it possible that I have an ovarian cyst?

Yes, it's possible - have you read this? Ovarian cyst - Wikipedia, the free encyclopedia

I'm sure you are aware that there is no 100% guaranteed "protection" so pregnancy is always a possibility.

What was it?