Congratulations Heather and Lisa!
Oh do I sympathize with the lack of energy and nausea. If I don't eat every 2 hours I'm totally faint.
About workouts, I've just been forcing myself to stay with my rotation. This is my third pregnancy with Cathe. I do Cathe modified as needed--lowering step height, taking out jumping, etc. I love all the new low impact vids she's done because not only are they great options in and of themselves, but they also give my lots of modification ideas. I've learned to get really creative so that I can keep working out with her. I also use our treadmill and stationary bike a lot.
For weights, the only modification I really do is to put my bench at an incline for all work on my back. I am able to continue with my regular strength training programs otherwise.
Anyway, just listen to your body and your doctor and I'd say, don't push too hard. Save that for after the baby comes. That weight will come off. I always gain a ton of weight and with hard work and persistance it pretty much comes off after (although as I age, diet becomes more important in that endeavor, but that's another topic altogether)
Again, I'm so happy for you both!
Maggie