Why Are My Periods Very Light With Brown-reddish Discharge, Bloating, And Weight Gain?

I have very light periods where my bleeding was nonexistent. I’m a 34 year old not pregnant, currently experiencing brown-reddish discharge. I’m taking iron supplements atm also my thyroid test came back normal and experiencing difficulty in losing weight. I weigh 58 kg which is too much. My belly seems bloated and exercising increases weight instead of losing. What should I do?