at 8 weeks, she shouldn't be up for more than an hour. it looks like she's up for an hour and a half sometimes. that may make it harder for her to nap. also it looks like she eats more than 3 hours sometimes. she's really young and 3 hours is long enough.
at night, she's up at 5 and bedtime doesn't start until 7 and that's what i do for my 6 month old. i know it's a hard time having the rest of the family to help out. but the other family members aside, when she gets up at 5, i would bathe her and prepare her for bed then feed her dinner at 6. she should be in bed no much later than 6. i always had a hard time with the last meal because it doesn't fall right. for her to only be up an hour plus eat after 3 hours, she'll be going to bed just a few minutes after eating but i think as long as you don't feed her to get her to sleep then she'll be fine. maybe after eating, she can tell everyone good night and you two can go into her dark room and sing to her and then put her down by 6:10. then you can finish getting dinner ready.
use the catnap to start dinner and leave it simmer. my best friend became our crockpot because it required so little when i was busy with a baby.
now, you're concerned about how bringing your son to school and picking him up will affect your baby's routine?
lastly, a thought about errands, is it possible to leave her behind sometimes? does she get over excited in the store? it may take her a while to settle back down with all that stuff going on around her. when my lo takes power naps in the car but not a full naptime, then when we get home, she wakes up but can't get back to sleep so she doesn't get enough sleep.
i'm sure it's really difficult juggling so much. it sounds like you are doing a good job though. she at least is on some kind of routine and that really helps her.
melissa