Periods after Baby?

Rachel

My 2nd daughter is 5 months 22 days old and last month I experienced my first period since I had her. it was pretty normal (5 days, heavy then moderate then light bleeding) but the start date was Aug 12th. I'm now 7 days past due with what glow says I should have started this month. I've taken 2 pregnancy tests. one a day before I was due to start and again yesterday. both negative. Have any other moms had post baby periods like this? I don't know what to expect. I'm on the bf*ing mom's birth control pill but as of last week I'm no longer bf*ing. waiting for an appt with my ob to switch pills.