It could be either one, because the morning after pill is only about 80% or so effective. There are a lot of side effects with this pill(causing your period to come late or early, cramping, nausea, etc), so I would guess that is more likely to be the cause than pregnancy if you took the pill on time(sooner the better within 72 hours). I used it once before and had bad cramping plus nausea as a side effect. This pill is not meant to be used more than twice in a year and really should be avoided at all cost if possible. I'd make a doctor's appointment and look into all of the birth control options, finding out which would work best for you, then start using that. Since it has already been 2 weeks, you can take a home pregnancy test and get an accurate result. That may help put your mind at ease. Hope it goes well.
thanks for the advice and information! much appreciated.
No problem. Good luck. :)