If you had a blood test and it came back negative, I would say your chances of being pregnant are pretty much nonexistant because blood tests are rarely wrong.
The symptoms you're feeling could be anything, or you could just be so scared of being pregnant that you're body is playing very mean tricks on you. Trust me, I went through the same thing last summer - I was always sleepy, got sickened by certain smells, was eating more, was very nautious and had a very very bloated stomach. The only one of those that was not imagined was the nausea and bloating - I had contracted a stomach bug that created a lot of gas and just made me bloat like a bubble.
Have you had your period yet? Were you due and missed it, or was late on it? If it was, i'm going to bet it was so because you have been stressing - as I said, if you took a blood test and got a negative reading, then I would say you're fine. If you are still very nervous, I suppose you could have another blood test done.
I know it can be really scary to think that you might be pregnant and you'll be stressing about everything thinking you are when you probably aren't. Just try to relax because you're making yourself sick over it all...Yeah, easier said that done, right? Haha, you'll be just fine, hon. Deep breaths.