@shilowh,
Most likely you are not pregnant - although there are cases when a test comes back negative. Have you tried another pregnancy test? I know one time I took a pregnancy test and the line or whatever it is that tells you if you are positive was so very faint. It was early in the testing process so I waited a week took it again and it came back definately positive.
You may want to wait a week or so since you took the last and see if the results change. Have you missed periods before or been late? Stress can definately cause this to happen and could be simply the stress of being concerned about an unwanted pregnancy. Is there a doctor you can see? They can provide you more guidance than we can.