HI Sissy,
I was also exhausted during my first trimester. I woke up about 7am - no shower - went to work and then came home and took a nap. Then I'd have dinner and go back to bed by 8:30 pm. The weather was beautiful and all I did was sleep; no workouts, no yardwork or housework, nothing. (I was lucky and had no morning sickness and no toddler that needed my attention). You will feel better soon; don't beat yourself up. I read on one of the websites that during your first trimester, the energy expended by your body due to all the changes your body is going through right now is comparable to running a marathon each day.
If you and your doctor haven't done so already, double check your thyroid (TSH). Pregnancy can often whack out a perfectly normal thyroid (and it usually goes back to normal after the pregnancy).
Good luck and congratulations!
Denise
Chloe: due march 5, 2010