Short Periods Cycle, Less Than Normal Bleeding, Suffering From Colds, Running Nose. Taking Medication. Causes For Abnormal Periods?

Hello, I m a 30 year married woman, i got married one year before. Till 6 months my periods was normal, after that i shifted in XXXXXX. My height is 5 inch 6cm and earlier my weight was 52kg. after shifting in XXXXXX i gained 8 kgs weight. Now i am having problems in my periods and and having a good flow only for one day. This month flow is really less than normal on first day also. I went to a doctor and did all test. All reports are normal so doctor told me to reduced weight. I m doing exercise from last one month and still this month there is no change in my periods. Earlier my flow was normal for seven days and frequency was every 21 days. I m taking healthy diet . There is one more thing , after shifting in XXXXXX i m suffering from running nose so i used to to take cetirizine tablet. Please suggest me something. what should i do, i m really worried.