Vasectamies can fail, but more than likely your body is just adjusting after the shot. Take a test if you are worried as it can do no harm. Good luck
The shot is very tricky i only had a period once a year after being on it for so long. i felt horrible after getting off it throwing up every pregnancy symptom known now that i am pregnant i have no bad symptoms. its a very tricky birth control i say no it'll take a while for your body to work that stuff out it could effect your period.