Could I be pregnant?!?

The last time I had was on January 13th 2010. I had my period in Januar, February, and March but haven't had one for April. There was a time in April that I cramped really bad and had all the signs of starting a period but it never came. I'm not sick and I don't appear to be gaining weight. I took 2 over the counter pregnancy tests (one at nite and one in the early morning) and they were both negative. Could it be possible that I'm pregnant and not know? My periods are like clockwork so I'm worried why I didn't get my period this month. I have one daughter and didn't show with her til I was like 6 or 7 months...but I don't even have a bump?! Please give me some advice!