Irregular periods after birth

Kaitlin Jackson

So I gave birth to my son a little more than 4 months ago. Sadly he became our guardian angel the day after he was born. My Dr said I start trying to get pregnant again 3 months after giving birth, but my periods are incredibly irregular. Like my period is almost two weeks late, and I'm not pregnant. Is this normal? Should I talk to my Dr? I'm trying not to stress out about it. I know that makes it worse.