It will get alot better once you get toward the 2nd trimester. If not, I agree with PP - evaluate your supplements. But being super tired is totally normal in the 1st trimester, even if you don't have problems with anemia or anything.
It does get better!
I felt awfully tired from week 7 to week 8. Just walking from room to room would make my heart beating like crazy jumping out of my chest (I'm not overweight and usually am pretty energetic). It was so miserable; I had to lye down right on the floor so many times to have some rest just from walking a few steps! I also had the worst nausea that week, so I was feeling so extremely bad!
But after week 8 it began to ease up a bit and now it's much better (both energy level and nausea; I'm at week 10).
I hope you feel much better very soon and have the rest of your pregnancy nice and uneventful!
sleep a lot and try to get some exercise even though it seems counterintuitive. Most likely you'll feel better when you hit the second trimester...and enjoy it because now that I have a todder and am pg I'm just tired no matter what and 18 weeks!