Okay - I think I made it through the week being a single mom - I'm still standing (or sitting or laying down when possible). My husband is back and so I hope things get a little easier.
We are now on a three-hour block schedule pretty consistently. My DD eats every three hours starting at 6 a.m. and my DS gets up around 6:30, so I try to get my DD fed and let my son come in to her room when he gets up and I read a book while my DD finishes nursing. Here is the rest of the day:
E 6 a.m.
A 6:40-7:15 or 7:30
Take DS to school (day care)
E 9 a.m.
A 9:40-10:15 or 10:30
S I rock her and often give her a pacifier while she's in my arms. As her eyes close and she stops sucking, I gently remove the pacifier (if it hasn't already completely fallen out of her mouth) and then put her down in her crib. She usually wakes a bit and cries for 30 seconds to a couple of minutes before settling down for her nap. (This is typically how she naps whenever we're home - if we're out and she's in the car seat, she usually falls asleep without crying.)
E 12 noon
A 12:40 - 1:15 or 1:30
E 3 p.m.
A 3:40 - 4:15 or 4:30
This next nap is usually in her car seat so I can pick up my DS at school.
E 6 p.m.
Then, rather than letter her have "awake" time and then CIO or try to go down in her crib, I put her in the sling so I can get my DS fed - we usually try to eat around 6:30 (my husband often gets dinner ready, except when he's out of town of course). My DD is in the sling or in my arms (often with the pacifier). She has also been gassy lately (so I'm removing "gassy" foods from my diet to see if it helps), and she seems now to be especially gassy at this "fussy" time. Some nights I have been able to put her down for a half hour or so before she eats again, sometimes I just hold her the whole time - while I'm getting my DS fed, ready for bed, etc. I have been putting her down for at least 15 minutes (even if she's crying) so I can give my DS a few minutes of attention - even if it's just to give him a hug, get him tucked in to bed, and rub his back for a few minutes.
E 9 p.m. (this is her one bottle of formula, which my husband gives her - unless he is out of town of course)
I then change her diaper, swaddle her and put her right down - she goes down easily (at least so far).
She wakes after 3 or 4 hours (each night is different) - so somewhere between 12 midnight and 1 a.m. she is usually up for another feeding. Again, she then gets a diaper change and re-swaddled and then goes down to sleep.
The last night waking is usually around 4 a.m. where we do the same routine.
I then get her up at 6 a.m. to start the next day.
I think we have a pretty good schedule down now - she is 6 weeks old on Monday, so I feel like we got into a routine that makes sense for her age. I'd love to make the fussy period easier, but the rest of the day/night is pretty good.
Also, I may change to cluster feeding and a dream feed next week - we'll see what happens.
Thank you all for your advice and encouragement.