I just had my first child at age 40 and of course my experience is similar to yours. I can't help but wonder if delaying (or eschewing) having children is contributing to what seems to be a broadening generational gap. I'm learning lessons in early middle-age that previous generations learned in their early twenties. I could have used some of this new empathy I'm feeling for my parents and their generation 15-20 years ago.
Same boat, same feeling. But I also think there are mistakes we aren’t making, a maturity that will lead to perhaps enhanced outcomes for our kids even if not for us.
Not GP, but I suspect that increased emotional maturity would prevent one from lashing out, overreacting, underreacting, being unable to emotionally support one's child, etc.