1) As someone who is disabled from birth, that comes off as terrible as it gives people a right not to have well, me. I know you don't mean poorly, but it smacks of eugenics to me.
Someone close to me has had two children. The first was a girl, and healthy. The second one only lived about 9 months. It turns out that both the mother and father are carriers of a very rare genetic disease (disease may not be the correct word here; syndrome might be better). The child drained their bank account due to having to fly out of state for doctor's visits. Their entire life savings was gone. Fortunately, their community rallied around them and helped them out.
In this case, are you seriously saying that since they know that there's a 50% chance that another child would also have to have the same care, which they couldn't afford the first time, they should still try to have another child?
Keeping also in mind that they had to have thousands of dollars raised by their community to even afford to visit the doctor. And the emotional trauma of having a child die, and knowing that if their next child had the same issues (50% chance of it) that the odds would be heavily in favor of the child dying within a year. Do you still think they'd be sinning by taking steps to prevent another baby?
2) This one gets me, as I do not yet have kids, I will hold off except to say that American society seems to have things to help with huge families. Well except vacations of course. Multiple kids to a room, buy a church van to shuttle everyone around, go to a supersized store like Costco and buy in bulk all the time, etc. I know people with very modest means do manage to raise a ton of kids.
Using myself as an example again, I have had many issues lately which I won't go into here. Suffice to say that I am on disability fixed income due to issues I developed while in the military. I can barely afford to feed my family as it is, and we don't do anything extra. No eating at restaurants, going to the movies, etc. We take advantage of coupons and food banks at churches. We also make sure to be a part of reward programs so that we get discounts on gas. The only thing we splurge on is once a week we get buy-one-get-one pizza at a nearby gas station. My daughters look forward to it every week and so I make sure to have a way to make it happen.
Point is, if I were to have another child right now, I would be blatantly becoming a drain on society, and disregarding God's commands that we take care of our families. I would be relying on the government to take care of my family for me.
3) Here I view a mother's portion to be with her children, giving her the time to give attention and pursue a part time career. However, if the mother is the breadwinner, possibly because her husband is disabled, I would say that the father can stay home to raise his children.
I'm not going to go into too much detail here. I know you didn't mean any of this in a bad way, and I'm giving you the benefit of the doubt there. But my wife is a very busy woman. She has to care for our three children as well as me. She has an in home business that helps with some money, and she home-schools our girls.
So, as you can see, another child just wouldn't work out for us.
With all this in mind, hopefully you can see how some of your reasoning could be upsetting to some. I don't think that was your intent. But in essence, telling people that it is a command to have as many children as possible is essentially the same as telling an infertile person that they are lesser because they can't have children. It's the same type of slap in the face.