Since your cycle is not normal at all I certainly wouldn't panic and immediately think pregnant. Personally I would take the time to think about a few things...have you had unprotected intercourse that might have resulted in a pregnancy? Even with an irregular cycle, are you ever this late? If you can answer yes to the first question and no to the second then by all means head down to the local drug store or supermarket and pick up an over the counter pregnancy test.
Sometimes its the Birthcontrol you are on as well! Mine is always messing up, being late, and not being normal! So I usually worry about being pregnant. But if you find you are having weird things like cravings, throwing up, or gaining weight, I would get a test to confirm or you may want to bring it up to your doctor.