Do you think I could be pregnant again (no cycle last month)?

Well back in 2007 I had my tubes done after my second child at a hospital that had a reputation of malpractice. But in December 2011 I had my cycle on the 22nd. Then in January I had it on the 24th. But I never did start in February and still haven't yet and lately I've been having cramps like I'm going to start but there's no bleeding. But I thought I should have started by now. I'm several days late and I'm not on any birth control pills, patches or shots. I just took a $1 test yesterday at lunch time and it came back negative. What do you think? Thanks!