What you are describing sounds like polycystic ovarian syndrome. Did you ask your doctor what your diagnosis was and why he wanted you to take this medicine.
However, if it is PCOS, then metformin is an appropriate treatment. You also have a high risk of developing diabetes in the future, so this is a good time to focus on staying active and following healthy diet.
Best wishes
We cannot diagnose nor exam you over the inet. Besides helping to lower to glucose [blood sugar] levels metformin is Rx'd to help with weight loss. Your prescribing doctor has your medical records and history and should be the one to direct your medication questions to.