Need advise please


So have been on birth control for 2 years now, and have had my period spot on every month. They come wednesdays. Well I was supposed to start Wednesday and I didnt. Tuesday I had a couple spots when I wiped. Then nothing thursday I took a test it looked negative so I've waited but now its 3 days last when I should have started and still nothing. Think this is pregnancy? Or could it be something else?