Hi C.,
Like the others said - pat yourself on the back for WHATEVER you get done. You only have 2 hands and 24 hours, and unfortunately as Moms we may need 3 times that, but we only can do what we can. I think you're also overwhelmed because you just went back to work, and it's a new schedule. I was the same way for several weeks, but finally I got adjusted to it. What helps is once my DD is in bed by 7:15 I prep her lunch for the next day and get her bag ready to go out the door in the morning too. Once or twice a week I'll also pre-prep dinners for the next 2 nights. I make VERY simply but healthy meals - grilled chicken (which you can pre-grill a bunch at one time and then eat them throughout the week), cut up veggies for a stir-fry, etc.. Pre-planning simple dinners has made things a lot easier especially now that my DD is old enough to eat table food too. Knowing exactly what you're having for dinner helps because on the way home you'll be subconciously thinking about how you can quickly prepare it - and you'll also learn to pre-plan them ahead of time to make it easier.
I also lay out hers and my clothes the night before, do a little light cleaning up, and then SIT DOWN by 8 or 8:30 pm and relax! This can either be watching a little TV, talking with DH, catching up on computer stuff, scrapbooking or sewing (my hobbies), reading, or somehting else that lets me really wind down.
Take it easy on yourself - you're just getting the hang of a new baby, new schedule, etc.. you're doing JUST FINE especially if you're worried about doing it all - you're probably doing a lot more than you think!
T.