I know how you feel, I was like that for 9 months, even in labour!! Plus I had heartburn on top of it. Be very careful that you don't get dehydrated like the others have said. My doctor said as long as you're drinking water, that's the main thing, even though as soon as I did drink some, I'd throw it back up, then have some more.
It is very hard, and does unfortunately make the pregnancy drag on. Do what is best for you regarding work. I had to give up work at 5 months, and found just resting at home worked wonders for the energy levels. Are you taking a pregnancy multivitamin? That will help with your energy levels. Is there any foods which you can keep down? Funnily enough, milk drinks helped me.
If it gets too bad, see a dr, if you get too dehydrated you'll need a drip put in.
Good luck.