Gone :)

They say after a couple months of not having your period to go get checked out. Stress or anything really can delay or make you miss a period. I have had very regular periods all my life and have missed periods before because of stress. They always came back and on track. I doubt you are pregnant. You can request a blood test for pregnancy though if you still think it could be that.
As far as leaking colostrum, that isn't anything to worry about. I leaked milk a year after I had quit breastfeeding. Hormones do crazy things to women. lol

Plan B can cause your period to be late.

I'd personally wait it out a few weeks and just be mindful of not drinking ect in case of the off chance that I was actually pregnant.

I waited until I was ten days late.. My OB did a blood test and gave me a script for Provera .. Said if the test came back negative then to go ahead and take the medication To jump start it. I was TTC though so getting my period on track was a big deal to me at the time

Quoting ℳonster's ℳom:" The on call Dr explained that to me but my period after Plan B was black old blood so I've had a few ... [snip!] ... blood draws and I can afford them without insurance, but how long should I wait for AF until I make an appointment with them?"

I'd personally wait a couple weeks just cause I'm cheap LOL!
But I mean you don't need to wait. A blood test should pick up pregnancy as soon as 8 days after ovulation.