I am close to 17 and I hardly ever get my period, I am very overweight. What should I do?

Consult your doctor.

Over weight can have a issue on this, but there is no way to know without a full medical check up

Check with yout doctor and see my sister might have to go on birth control because her periods aren't right

Talk to your doctor, tell her that you have irregular periods and that you don't know why. A gynecologist would probably be your best bet. I got my period when I was ten. I don't get it now because I am on the depo shot. Maybe you need the pill my mom and my big sister both are on the pill because of irregular periods and pain and my mom is going through menopause it helps stabilize your mood.