Hello and welcome to Share. Have you been to see your OB yet? That way you'd know exactly how far along you are, as there can be big differences in your energy level based on what trimester you're in.
In general, the first trimester is pretty exhausting. There are those women that feel great and have tons of energy, but I don't know them. ;) At your first OB visit, they will take several blood samples to test you for anemia, and other conditions. Bring this up just to make sure that everything looks good. Are you eating well? It takes a lot of energy and nutrition to grow a little human, so make sure that you are staying hydrated and eating good healthy food.
If you are able to, my suggestion is to sleep as much as possible, but also let your OB know your concerns to make sure this is typical pregnancy fatigue.
Congrats on your pregnancy!!