Should I be nervous?

In March I was taking flagyl for bv and I’m on birth control and had intercourse a few times. I heard afterwards, mixed things about antibiotics affecting birth control but also that mine wouldn’t. My gynecologist didn’t say anything either and it wasn’t in the booklet. I had a 7 day period that seemed normal. This month I’m on it currently, it’s day 3 and seems light already. Usually it’s 6 days long. I’ve taken tests though and they’ve been negative. Any advice?