16 dpo..still no AF..but no bfp either.

Soo AF was due two days ago..and I'm never late. If anything I'm early. I've had cramps very similar to AF but there has been no blood or sign of it whatsoever. In fact my cm is completely white and lotion like. Took a test yesterday morning and it was negative.We had sex last night in the hopes of starting AF and nothing! Other symptoms included very heavy boobs and lower backache. How long should I wait to retest?