How many children do you look after each day? Is it the baby all day every day, then an additional two children, or is it other grandchildren as well?
To be honest, you should be scaling this down completely, across all fronts. I think you need to prioritise your own health and well-being (especially as you are a carer for your husband). Looking after small children is physically demanding - if you have a fall, and eg break your hip, that will change everything, especially in terms of whether your dh can be cared for at home. I can’t believe you have spent 10 years tied to school pick ups and drop offs, and childcare of small children. You have been completely selfless.
I think your dd needs to get new childcare in place. Maybe scale it down to having the school-aged grandchildren after school one day a week, and do not have the youngest one at all. Or stop doing regular childcare entirely.
My mum had some falls in her mid-late 70s because she was having to do additional caring responsibilities for family members, and it was too much for her physically. Knees / ankles / spine all irreparably damaged, and now she is a wheelchair user. Please prioritise your own health and well-being - you should be able to spend your time doing gentle exercise, meeting friends, doing hobbies, resting - and also enjoying time spent with your dh while you still can (if the dementia is not too advanced). Sorry to be blunt, but this is not a dress-rehearsal, it sounds like you are being completely taken for granted, and if you do not start to put yourself and your dh first, you may come to really regret that in future (my mum does).
In case your daughter takes you for granted and doesn’t tell you - thank you for being such an amazing and selfless grandparent for the last 10 years - but it is time for you now.