I am pregn. Period 2/20. Sex on 3/3, 3/6, and 3/9.I started to have cramps, bloating, and white lotiony discharge on 3/11and after when was conception?

Conception. There is no perfect way to determine your conception date (unless ivf). With a last period beginning feb 20 you most likely ovulated on march 5-6. This is based on regular 27-29 day cycles. Sex on 3/3 or 3/6 are the most likely events. Sex on 3/9 was probably too late in your cycle.