Help...

Hey ladies! I got the depo shot about what's coming up on three months ago cause July 18 I would go back for another one but I'm not cause I don't like the shot and have decided to try for a baby. Anyways Me and my s/o  have had sex multiple times without a condom this month and lately I've been eating a lot, have had Horrible stomach cramps, frequent urination, headaches, dizziness and nausea.....Is there any possible chance I could be pregnant. I saw online many people have gotten pregnant while on Depo or any form of Birth control...has this happened to anyone else before? Have any of you ladies gotten pregnant on birth control.