Chocolate cyst of ovary is a sign of endometriosis. In this condition the inner lining of your uterus grows in places other than the uterus like the ovaries, tubes, peritoneum etc. This tissue also behaves like the endometrium. It grows and sheds when you have menses. Chocolate cysts can increase or decrease in size. Your cyst is quite big and might need surgery. Try to conceive as early as possible since endometriosis is progressive disorder and you may face problems for conception.