It does seem cruel that most moms-to-be feel worst during the first 12 weeks or so, which means that until you announce the good news, there's no milking it for (well-deserved) sympathy. The only real cure for first trimester fatigue is sleeping more—which, to be honest, might not even help. Go to go bed earlier, sleep as late as possible and try to make it through the day.
To boost energy, eat small, healthy meals and snacks throughout the day. Go for protein and complex carb combos like whole grain cereal with low-fat milk, a piece of cheese on whole grain crackers or a couple of slices of turkey on whole wheat bread. And when you feel yourself sinking into a valley, do some stretches and deep breathing exercises or go for a brisk walk around the block.