Waiting for my period after taking plan b?

Help help help.. Condom broke april 30th (sat) took plan b early in the am on tue. around the tenth or so i spotted a little.. not too much just that on day. I took a pregnancy test yesterday, it's neg. I still have not got my period.. yesterday was abut the time I should have got it. I have been stressing to the max about this and some other stuff that's going on in my life right now as well, I know stress will delay a period. Whats going on???? is there anything I can do to speed up this period?? was that spotting my period or should i be getting another after the spotting? if so how long? i know the only thing is just wait.. but it's killing me!! also starting today I have been having this pain in my lower belly.. kinda like a consant throbbing.. weird.. please, any help would be awesome!!!