Pcos and light periods. After 3 months?

I've been diagnosed with PCOS and hypothyroid 2 nonths back. The doctor gave me pills for thyroid, which I consumed for a month and my thyroid is normal now so I've stopped taking the pills. The doctor gave me tablet Ginette-35mg to get my periods, I took it for 21 days and got my periods on time, however I've also gained 2 kgs weight which is most probably because of the pills as my eating habits are still the same. My question is that I'm getting my periods on time now but they only last for 3 days and the bleeding is very minimal, before when I used to get my periods naturally, it would last for 5 days and the bleeding would also be normal. Is light period a cause of concern? And should I continue taking tablet Ginette-35mg for 3 months? What treatment should I undergo after 3 months?