Help-bleeding 9 DPO... worried

Hi ladies, if anyone could please help me with your thoughts/experiences? I ovulated for sure with my peak day on May 28th, and had strong positives a day or two after that as well... then woke up today June 6th with some bleeding (didnt notice till i went to the bathroom and wiped.. it is dark reddish and not a ton, but I do have a pad on and its slowly coming out). Was shocked because im only about 9 days DPO and my period isnt predicted to come until next week. Side note-this is my first period or bleeding since giving birth to my son 20 months ago i nursed him until he was about 18 months...

I called my OB but he is very nonchalant naturally and said he doesnt see an issue even its my period at 9 days DPO

-Is it normal to have a period 9 days DPO?

-I’ve read about implantation bleeding but not sure this is it.. I’m lightly crampy

-I read women who experience this consistently may have a luteal phase defect getting their period before 10-12 DPO which can cause infertility? Im 34 and we really want our 2nd child soon so any issues I want to diagnose asap

Thank you so much