T.H.
I would wager to say it's just wacky hormones, but I'll just toss this out there...sometimes vasectomies don't take, and maybe you should just take a pregnancy test to be on the safe side. I'm sure that's not it, but you don't want to find youself on the show "I Didn't Know I Was Pregnant!" haha! Ride the wave (or lack thereof, I should say) and chalk it up to hormones, I would think it's fairly normal in the first 12 months post birth!