There are a variety of reasons that your period could be late this month, from delayed ovulation caused by a mild virus to pregnancy and the only way to find out is to start by eliminating what is NOT causing your late period.
First, you should take a home pregnancy test. If that comes back negative think back - have you been stressed, ill or experiencing a significant change in weight? All of these things can contribute to a late period.
As for the period that arrived a few days early in February, unless your periods continue to be irregular for the next several months, that's probably not a big deal and happens to most of us once in a while.
If your period still hasn't started in the next week, go ahead and give your doctor a call and let them know what's going on.