could I be pregnant? negative test

Okay, I need some perspective! I am 12 days late, increased discharge, cramping, almost constant erect nipples (weird right?), back pain, and to top it off, I ate waffles the other day. Waffles! I'm not a pancake/waffle person...but I was when I was pregnant. I have a seven month old and I'm on birth control but I had a stomach flu on the 26th and threw up my pill for that day. I've taken a few tests that have both had weird results like ink blobing a little on where a pregnant line should be but no tests that are actually positive. Anyone have a similar experience? What happened? And if I'm not pregnant, what the heck is going on?