Not all women get early pregnancy symptoms, I didn't get any for about 6 weeks, yet some people can tell right away.
Many things can make your period late though, it could be stress, a change in diet, certain medications, illness, weight loss etc. Or, it can just be a hiccup in routine.
Most women will experience a late or missed period at some point and there is often no real reason.
If your period is normal next month, there is nothing to worry about, it is one of those things. If it doesn't happen again next month though, it is worth seeing your doctor to check there there is nothing going on medically.
Just to be sure, I would be inclined to take a pregnancy test. If nothing else, at least it will stop you worrying, and that in itself may be delaying your period.