If you had a period with the normal amount of flow and length, you are not likely to be pregnant. You can confirm that the morning after pill worked by taking a pregnancy test no sooner than 10 days...
If that period, after taking the MAP, is not your normally scheduled time for your period then it is only a side effect and not a period. The only way to tell if the MAP worked is to take a HPT.
It could be normal, if you were expected to have your period around that day anyways. Did you take your morning after pill, and did you know that your period was supposed to arrive that day or the...
This does sometimes happen with MAP. I wouldn't be too alarmed but as a rule of thumb, I always recommend that a pregnancy test in performed in 2-3 weeks as the result will be accurate.