2 weeks overdue and now I'm on my period again.

You can still take a test.
I know someone who had her period 4 more times while she was indeed pregnant.
That just happens (very rarely)!
But it could also be that the embryo was rejected right away, but that usually happens after about 3 days, not after 2 weeks. In that case, it would already be a miscarriage! You would have felt severe cramps!!?
It could be implantation bleeding; then the fertilized egg floats around in the uterus for up to a week after a 4-day journey through the fallopian tube before it finally implants (late), which can cause some blood loss..
So the question is: Did it feel like a normal period to you??