Once my periods regulate again will i lose a few pounds and my metabolism go back to normal now i've stopped the injection (depo provera) ?

Yes: The side effects of depot Provera (medroxyprogesterone) are super frustrating. Progesterone in those high doses acts as an appetite stimulant and affects your hormones --> contributes to weight gain. After you stop the depot, you're going to want to try calorie restriction (maybe 1600 a day?) and exercise 30-60 min a day. 'my fitness pal' is a great app/website that can help you with your goals. Good luck!