Oh! When you said you were at school I thought you may have been young - like 16/17 - and that might mess with your cycles...But your not! lol

Well, I would hang in there until you take the next test...being an Honours Student would be pretty stressful, and since you stopped taking the pill so long ago, you should be back to normal by now.
I know it's hard, but try not to worry...you cant do anything about it either way until you know for sure, so test again when you feel comfortable, and let us know how you go!