Period question.. Trying not to get anxious

So... I had a baby boy 4.5 months ago. My cycle returned 6 weeks after giving birth. I've had 2 very normal cycles, things got very regular right away... I was suppose to start my 3rd cycle 3 days ago now.. I found the tiniest tinge of brown cm only because I checked due to it being late, still nothing more... With my other 2 kiddos my periods returned right away and we're instantly normal cycles... I can't help but get anxious... I am certain I ovulated, I'm have very definitive tell tale signs of ovulation. So... It's normal for your period to get normal after pregnancy and then flip a switch all of a sudden... Right?!