Could just from you getting ready to have your period. PMS symptoms really resemble pregnancy symptoms. Are you taking your pill regularly? That being said it could be possible you are pregnant as birth control pills are not 100% effective esp if they are not taken properly. I know a few people (my mother in law included) that did get pregnant on the pill. I would really suggest using condoms as well as the birth control pill if you really don't want to get pregnant right now. Good luck hun but try not to worry too much because it is probably just your period symptoms.
There could be a chance your pregnant but its really unlikly it could just be stress and that you aint had you periods for 9 weeks just relax
If you're due to have your period soon, just wait for it to come and if it doesn't, take a test. It is, however, possible to get pregnant even if you're on the pill. Have you missed any pills lately? What symptoms are you having? Oftentimes, the symptoms of an upcoming period can be mistaken for pregnancy symptoms.