The pregnancy will still show up on home testing kits, and if you are a few months gone that it will be very accurate. Do a test, and if its negative and you're still worried, you can always go to the doctor anyway. If you've been having your periods its very unlikely that you are pregnant.
In this sort of situation, you can often become convinced of something thats not true. In the weeks after my pregnancy scare, I became convinced that I was pregnant, because I was feeling sick, I was sure that my stomach was sticking out further than usual, I thought I was putting on weight, and my boobs were sore. The reality was that I was so scared of being pregnant that to some extent, my mind convinced me that I was.
Go to the doctor and try not to worry too much.