2 weeks late and tests coming up negative?

I am taking Loestrin birth control pills, normally my period is predictable almost to the hour (no joke!) and this time around I am 2 weeks late, I've taken a pregnancy test a couple days ago (89 cent cheapo one) and it came back not pregnant. I have had unprotected sex recently, could my test have been defective? I am also extremely bloated and very crabby and emotional the past 2 weeks. Any suggestions? I am going to go get a different test in a bit, just wondering if it's going to be a wast or not. Thanks!