@MrsDinero, I think you should experiment with how much of your future goals you can integrate into your life now.
Your own remarks suggest that your financial life, including earnings, saving and investment, are well optimized.
Your own remarks also suggest that your goal is time with the kids. You are working now to have time with them later, but since you're on track financially, the next optimization is some extra time with the kids now where possible. You don't really need to optimize, but if you're going to do so, that's where you should do it.
Can you increase work efficiency to allow a few free afternoons? Replace the nanny occasionally, or join him/her once in a while, depending on what is reasonable in the employer/employee relationship?
Or maybe focus on the quality of current time. Journal/blog/insta the good times with the kids? Bone up on child development for insight on how to make the most of time together? Focus the journal/etc on the emotions, to attune your instincts and savor the experience? Notice what they love best, and optimize family routines during the existing time to provide maximum flexibility/tools/settings for the things they love? Find ways to thank husband for his role too in making all this happen? Do pro-kid things I can't think of?
Imagine if you get cancer next year and have 2 years to live. What memories can you make with them between now and then?