Hey, I'm newly married and me and my husband are TTC for 3 months and since then, my periods are…

Hey, I'm newly married and me and my husband are TTC for 3 months and since then, my periods are disturbed. Menses starts with brown threading and then after 8-9 hours, bleeding starts, which lasts for 2 days only and on the 3rd day, it's so much less and stops. Though before marriage, my cycle was so normal with 5 days. Doctor adviced me take multivitamin so I'm taking becefol and cal100+ since last 2 weeks. Can anyone please help me with this, is there anything to worry about? Also, what's the normal time period to conceive? My age is 23, female, 63kgs weight and 5ft 3in height. Thanks