I would love to be a SAHM. But like OP said, my working is not optional for us. DH makes enough to cover the mortgage and basic utilities, but then there's still necessities like um, food. And clothing for the kids (even yard sales add up). And medical care (DH does have insurance through his job, but with a huge deductible, and so all medical costs come out of my paycheck).
I work as a nurse. I'm glad that I went ahead and finished school after having DD, but I still find it to be very stressful. Sometimes I feel like I do a lot of good, but sometimes it is pure adrenaline the whole shift. Since I never know which shift will be a bad one until I actually get there, I have a super high anxiety level before each shift, and then afterwards I often have a very hard time leaving work at work. Nursing pays well, which I'm thankful for, but for the most part I feel that it is so stressful that I doubt I will stay in it much longer.
Currently I work part-time nights, which I thought wouldn't be bad, but between the commute (gone for 14 hrs each worknight), the stress and the exhaustion, it's just not working so well. In January I'm taking my schedule back to per diem. The funny thing is, I'll still be working about the same amt of hours (have to), but I know it will feel different just due to having more control over my schedule. I've done per diem before and loved it. No benefits, but it's the closest thing to SAHM that we can afford.
There are a lot of positives to working, and I try to focus on those. But I definitely would SAHM if DH made enough money. He knows that, and I try not to complain, because then he feels guilty and depressed over not having more earning power. I love that he has such as strong relationship with the kids, and I'm not sure they would have that if I was here all the time.