If you are getting your period in any from, regular or irregular, you are not pregnant. If you still worried about being pregnant then take a pregnancy test. You would know if you are having a tubular pregnancy or not because that form of pregnancy causes server cramps when the egg starts to grow and there is no room for it. If you cramp to the point that you think you are going to die than head to the hospital and have them check it out. Other than that you're fine.

Good luck!

There is sometimes bleeding during pregnancy; my mother was 4 months pregnant one time before she realised it, because she was still getting a light period. Please go get tested!