I was a SAHM for 8 years, and after a while is WAS the hardest thing I've ever done, mostly because you are 'entertainer' for most of the time and it can be very difficult in 'funny' ways, constantly being creative and upbeat!
I am happier now I'm working again, I work full time, and although after childcare and petrol I haven't much left what I've gained in sanity is immense.
YANBU. Being a half decent SAHM is hard in many many ways, with hindsight my SAHM years were the glory years which I crave, already I long for that freedom of 'timetable', for that "I am the boss" feeling... but MY reality is that working full time is a LOT easier emotionally (though my goodness I miss my kids but come september they wouldn't be at home anyway!) the technical stuff, the housework, etc., well I get it done before and after work, and strangely its EASIER now I have less time to do it!
My ideal would probably be a decently paid job share, term time only, able to do the school runs... but I've found after 8 years out of work beggars can't be choosers. Chin up. Whatever we do as mums/parents there's a sacrifice, but all things considered, what each of us do has stress, pressure, and guilt involved to some extent... therefore YANBU, and neither is the next person who comes on saying they WISH they could SAH, or that they wish they could lessen their hours etc etc etc., we're all bloody awesome in my opinion, seeing it from both sides, and none of it is easy and lovely all the time. Savour it, time with BOTH children leaves neither out, but at weekends, if your DH is great, leave the youngest with him for a couple of hours and take the eldest off somewhere, even if its the supermarket doing chores!