baby #3?

I'm almost 10 months PPD and my period has been regular at 21 days since 4 months ppd. All of a sudden this month... nothing. I'm at 40 days since last period and no period, 2 negatives and one session of spotting (blood when I wiped first thing yesterday morning) and then nothing. I'm so confused and it is wearing on my husband and I both. Should I just call the dr? We planned on starting to try next month for #3 so we are ecstatic that may be pregnant, but this is a rollercoaster I don't want to be on anymore.