I assume it is unusual for you to have a menstrual month that is this long? Keep in mind, some women do occasionally miss a period "just because." If you happen to have not ovulated in January, you won't be having a period now.
Have you been having sex? If so, you might take a pregnancy test.
Hi. It's rough being a woman sometimes and dealing with this stuff. If you are a teen, it's very common for teen girls to be irregular. Reasons for all women that might make their cycle late are stress, illness, changes in routine, weight gain or loss, or literally some unknown blip on the radar. (as in it can happen out of nowhere). Agree that if you have been sexually active, you want to rule out pregnancy but otherwise, I would not be overly concerned about a late period. Doctors like girls to have a period every 3 months so if it goes beyond that, talk to your doctor.