BC Shot

I've been off of the shot for a month now & I'm having sex way more often with my boyfriend. I've heard stories where women get off the shot and not even weeks later get pregnant. I took 3 tests about 2 weeks ago, one was inconclusive and the other was negative. Opinions? I've had sore, sore boobs for a couple weeks now, not sure if that has anything to do with it but they are so tender and sore and idk why.