You need to be tested to know for sure. It is possible not to have any other signs. Are you on any birth control? Have you had unprotected sex? You need to either do a home test or just go to the doctor. Please don't assume you are not it is totally possible!!!!
it is possible you could be preg. no jokes about it. have you ever seen that show i didn't know i was pregnant? i'm talking about women who go nine months of pregnancy and only gain five pounds. actually one girl even lost weight. and they really didn't know the whole time until the baby came that they were pregnant. they even took at home tests that came up negative. you should just check it out for sure.
i wouldnt worry to much, just because your period is late doesnt always mean that your pregnant, there are many didnt reason to have a skipped or late period, of course one number would be pregnancy, but if you have ruled that option out, there are still many other causes, another one could be is your under alot of stress, also if you worry on getting your period sometimes your body can go into what is known as "stress mode" and will entirely skip it.