Finding yourself overwhelming fatigue during your 1st trimester....

There are actually two forces working against you:

•  Pregnancy hormone progesterone - acts as a natural sedative

•  Increase in your body’s metabolic rate that occurs during pregnancy. It's your   body’s way of ensuring that it can meet the nutritional needs of your growing baby. 

Best way to deal with fatigue is to sleep, hit the sack a little earlier at night-time and try to squeeze in the odd day-time siesta, if your schedule will permit it.
Most moms-to-be find that their energy level picks up during the second trimester (before dipping again in the late third trimester), so you should start to get some of your old energy back in a few weeks’ time.