Confused...

Emma • married November 2015, TTC since December 2015.
I ovulated really late this month (got a pos OPK on 20th/21st) which means I'm somewhere between 10-12dpo. AF was supposed to start yesterday... I have cramps like I normally would with AF, but no bleeding whatsoever. I've been late plenty of times, but I've never had cramps this bad for so long without actually bleeding. Any opinions on this?