Late, have symptoms but still negative?

C.E
Haven't had my period since around the 6th of April. I have some symptoms -- nausea, dizziness, just feeling "different," eating and sleeping a lot are a few -- but I keep getting negative results! Tried First Response but decided to switch back to Clear Blue Digital. 
One big symptom I don't seem to have is the chest (not sore, and look about the same to me). I have a blood test tomorrow to see one way or the other for sure, but could it be my brain playing cruel games with me since I want a pregnancy so much? It's felt so much more real than other times I "thought" were real. 
Thanks!