Advice

I'd have to say your cycle is still trying to regulate itself, its common to be late or missed that early pp. My period didn't regulate until 4 months pp, and I can still be a little late or early. Up to you if you want to leave it 2 weeks and test again, or leave it and it might just be your body trying to regulate

All I would say is my periods have been a bit all over the place since giving birth. I'm 7 months PP and would say it's just getting back to being regular-ish now! Breast feeding will also impact if you did that for any period of time.
However if the timings work with unprotected sex then could always request a blood test to confirm/deny

My sister didn’t get a period for a year pp. This is way too early to worry about that