I am 25 days behind in my period. I took 2 HPTs and both were negative. I also noticed some brown stain fluid, not enough to be my period. 2 days ago I took a blood test and it came out negative too. Yesterday I ate some taco bell and later I felt nauseus and threw up. Today I felt nauseous, it wasn't a strong feeling but it was nausea and it happened like 3 times today. I also had abdominal pain and cramps, but no sign of my period. Could I be preagnant even if the test came out negative? It would really be great news if I were, my husband is already thinking out names! :D:D

Yes, you can be pregnant (not "prego") if a pregnancy test reads negative.
There are multiple reasons this could be.

Eat a well balanced diet, and use your pregnancy test during your first pee of the next morning, for best results.

However, it doesn't mean you ARE pregnant. (not a positive test, I mean the late period)
Are you taking any hormone altering drugs? Not birth control if you are trying to get pregnant, but anything else? Including any fertility drugs?
It is uncommon, but not impossible, for these to have a reverse effect in some women.

I'm not taking any drugs, no fertility drugs, nothing. I'm pretty healthy and regular in my cycle.