I'm just going to throw this out there. Maybe it's stupid, maybe you've tried it, maybe this doesn't fit at all. But it''ll be out there in the universe and it may help someone. Leave your expectations and schedule at the door. Easy right? Harder than you think. I have 3 little girls 9, 5, and 2 and I am single. Sound hard? It is. But I get breaks and their dad is really understanding and appreciative of the hard work I put in with them surprisingly enough. But the thing is, I am a type A personality and it's not compatible with AP parenting. I try to schedule my kids and keep everyone on track and micromanage them. And it's not right. I find that our easiest days are the ones when we eat when hungry, sleep when tired, play, lounge around all day, and have nothing to do. When I am not thinking about when I have to do this or that or toss in a diaper laundry or get to the grocery store or squeeze in some exercise between snack and nap, etc. Those are the good days. When I am literally in the moment all.day.long. And it's harder than you think. But when you are focused on nothing but the kids and their needs, they are better behaved, you are more relaxed, and when they do get a nap or dad comes home and takes them to the bathtub, you will enjoy it more. You won't get that whining screaming moment when they come back to you that makes you freak out. I think it's just all about leaving the expectations of the day behind and letting everything flow. I will never be that "zen" mama that you want(and I want) but I have learned to control my temper at least 80% of the time and sigh and let go when I see the grocery shopping trip go out the window even when we are basically scrounging for food.
It's not easy. This is the hardest job in the world with the WORST bosses in the world and it doesn't get easier for many many years. But it's oh so worth it!