messy

I really dont quite understand this syndrome at all and would really appreciate a little feedback. I would have asked the last gyno I saw more questions but I was a bit nervous of him. Ive been told I have it going by my hormone ratio, and the fact I havent had a period for 3 years n 4 months now, so my gyno has prescribed the pill (microgynon I think). But what are the benefits of taking it to kickstart my periods exactly- I dont have any other symptoms except absent periods and an ultra sound showed no cysts. I havent gone to the doctor to get the pill yet, but if it does kickstart my periods- what does that mean? Do I still have PCOS despite them? If so how is it detected if the only sympton I had beforehand was absent periods? Im so confused! And I really dont understand the relation to weight! Im a bit overweight but not obese, and was told even just to lose a few pounds might restart my periods. But I just dont quite get it, I mean if I lost weight and had periods again, does that mean I still have PCOS or not, did my weight cause it or is my weight a symptom of it? How is it detected if periods start again? lol Im soo confused about it all, I know Ive asked some random, daft questions, but any info at all about the whole thing would be greatly appreciated. Im quite happy not having periods, so really want to know what it means if I kickstart them with the pill!