The Metformin most likely helped with the weight-loss. Due to you losing weight it helped your periods. Even if you are taken off Metformin it should not affect your cycle as long as you keep the weight off/continue to lose weight. For some people such as me, it did not matter what weight i was at I always had an irregular cycle. The only thing that helped was Birth control, for those that are trying to have children they do have other options however, they may cause weight gain.

Good luck on your weight loss and your journey. :)

I was taken off metformin and did not gain the weight back, however the metformin did not bring on my periods, my weightloss did. Good luck to you.