Confused..plan b problems!!

Eliana

I had unprotected sex on cycle day 6 (July 22) and I know he did not finish in me. I took plan b (generic Aftera) 5 hours later. I had some spotting about 6 days after taking plan b, and my period was due 2 days ago (I am on cycle day 32 now). I took 2 pregnancy tests of two different brands (one yesterday and one today) and both read negative. Any advice/anyone experienced this??