Birth control after chemical pregnancy

I am in the middle of a miscarriage after a chemical pregnancy, when should I start birth control again, I was on it, then lapsed for a month, and then the day I was supposed to start my period I found out I was pregnant, then a week later I started spotting and 2 days later started bleeding heavily (yesterday Jan 28). So I'm confused as to when to start back on bc. Any advice helps thanks!