OP, it might seem like an possible situation to change, but anybody can eat an elephant!
If it’s the career progression that upsets you the most, remember children aren’t small forever. Even part time, you could, potentially, get some more courses under your belt, go to conferences/courses, go for more senior shared positions (no idea what you do, I can do this in my job).
Yes, it’s not the same as being full time, it’s harder and it takes longer, but hey, it is what it is.
Also, you are your own person. Might not seem that way. But look, I suggest you do a mind map. In the middle of a page, write ME, circle it, and then write all your roles: mother, employee, wife, daughter, friend, citizen, runner, cook...etc.
Then,for each of the roles write 5 good things and 5 things you need to work on/you dislike/you want to change.
It will, hopefully, give you a bit more of a perspective, bite sizing makes a task easier.
Oh, and read ‘Wifework’ if you haven’t done it already. It will help you see just how many tasks you take on and hopefully will make you stronger :)
Hth