I enjoy lots of aspects of being a parent and I don't remember when I last cried after a bad day. DS is a typical rough and tumble toddler trying to assert his own independence. With DD nothing is ever easy. I think that is part character and part relates to my depression and how I related to her in early days.
You find what works for you.
I went back to work 3 days a week when DS was 4.5 months and I needed some time outside the house. I would not enjoy full time parenting. That doesn't make me a bad parent. SAHM is in my mind the hardest job in the world.
I try to make sure I find some positive time with dd every day and we do a bit of love bombing. If I am feeling overwhelmed I invite a friend round for her - changes the dynamic and gives her another outlet for her energy. I find two 4 year olds easier than one. I try to remember she is only small and reduce my expectations. We read an build a lot.
DH has a few weekends away coming up and I'm not looking forward to it. So I'll arrange play dates, maybe get the GPs to have the children for a few hours one day. Take whatever help I can get. Ask for it and plan it.
I do stuff for me. Running. If I'm getting jangly I whack on my trainers and go. Because my family need me to be as calm as I can be.
I have let my standards re housework drop like a stone. I accept that's just how it is (most of the time).
And I make sure out contraception is like Fort Knox. DH has had a vasectomy and he has agreed that whilst it would be hard for both of us if I ever get pregnant again he will support me in an abortion. I feel spread really thin and know that I could not cope with another child.
Generally I'm pretty happy. DH is pretty happy. The children are pretty happy. I can look at my reflection and say I'm doing my best and its not too bad.