Aww *hugs* Do cut back where you need to. You're going to need all the energy you can muster during the "4th" trimester, after Albi arrives. That's such a cliche but it really is true IME. As you decide where you feel called to trim your schedule, you might also think about which activities will be easy/hard to do with a baby around and then maybe focus your energy during pregnancy on doing those things that will definately fall by the way-side after baby (or on the flip side, let go of them now because you know they're on their way out anyway).
I'm starting to feeling the energy drain too, though it seems I only just got my energy back after a weary 1st trimester! One thing that's helped me, being the super over-planning type, is I that I drew up a weekly schedule (DS going back to school was going to change my schedule anyway). It's kind of ridiculous; color-coded and everything, lol. But a few things have really made a difference:
1) Setting-aside specific times for meals, snacks, and breaks during the day. Of course if I'm hungry I'll eat whenever but this reminds me to SIT DOWN and be still several times a day. I plugged all these times into my phone as appointments so an alarm tells me to stop what I'm doing and rest.
2) Setting-aside specific times for gentle excercise. For me that means taking the dogs on a morning walk and going to yoga one day a week. If I don't do this in the AM I get too tired in the PM and won't do it at all. A walk in the AM lifts my spirits throughout the day.
3) Designating when I will work, run errands, and clean house. It seemed like these activities either weren't happeing at all (uh, housework!) or they were running longer than I could sustain (errands and work). Of course there's flexibility but it helps me have a clear stopping point for everything I start. Just 15 minutes cleaning the kitchen makes a huge difference; so much better than not doing it at all or loosing track and scrubbing the floors until I collapse. Again, I'm using my phone to remind me when it's time to stop and shift gears.
4) Working out a weekly meal plan with DH. We settled on themes for each night of the week. Mon is soup/salad; Tue is frozen pizza (I work late); Wed is meat/potatoes; Thu is leftovers; Fri is Mexican; Sat is a wildcard; and Sun is pasta. I'm finding it so much easier to make dinner now. I've never been able to get into planning exactly what's going to be on the menu days and weeks in advance so this gives me a little structure and a little room for creativity. Plus DH and DS seem to appreciate that we're back to eating dinner every night, hahaha.
Good luck to you and to us all!