Plan B

While me and my husband are waiting for my appt to get my birth control back in, we had a "night" on Sunday for the first time since giving birth 6 1/2 weeks ago. There was no protection and I'm still in panic because I don't want anything to happen. 
I've been scared to take an emergency contraception because I don't want my milk to decrease or even stop as side effects...
Has this happened to anyone? 
Any feedback on taking these meds while breastfeeding?