The use of metformin is usually accompanied by a slight weight decrease and less often an increase. You need to discuss this with your doctor. I have been married for 10 years . In 1994 I had a ovarian cyst removed after skipping one annual check up the cist was 9lb. I thought it was just a heavy period until the mass actually passed the Dr.
Weight loss is the key to a successful pregnancy.
It sounds like you will also need assistance in getting pregnant, as the irregular periods suggest infrequent ovulation. You need to talk to your doctor about this. My cycle was always around 60 days long. I am not overweight and don't have a lot of symptoms. I have heard that a diabetic diet is good for this condition.