oh OP you are so frustrating, you are obviously an intelligent woman, but you are failing to see the real problem - it's not you having career aspirations, it's yours combined with your DHs - it's your DH's job that's the real problem!
from what you've said, he doesn't do shift work, so he could do closer to 9-5 hours, but he doesn't want to/you don't want the step down in income that will come with that.
Stop comparing the Nanny costs to your job, compare it to the difference between what your DH earns now, and what he could earn in a lower status, lower paid job.
If he moved to a 9-5 role and it wouldn't mean a pay cut of more than a full time Nanny wage, then he should be prepared to consider it. If the pay cut is more than a Nanny's full time wage, then perhaps you should consider that the compensation for his long hours is a wage that is high enough to fund the childcare he requires to work full time at this level.
It is his job that's the problem. He has a career that potentially could be child-friendly, it's just would mean at a level that doesn't pay that well, and probably be less interesting/challenging. (Or maybe not, depending on what he does).
What you have just accepted though, is that as the mother, if you aren't going to do the childcare yourself, it's your job to make sure you have it in place, compare the cost to your wage, and your DH can pursue any career aim he would like without having to make this his problem too.
Your DH's boss might not believe in being family friendly, but what about the competitors? Has he even tried to find a job with hours that work better for your family without a dramatic pay cut, or has he presented it at your problem to sort becuase he earns more?