"You mean I, a man, can't have relations with my wife for a whole 10 days a month? Does God really intend to punish men that way? I don't think so."
Fact: If you want to not have a baby, NFP reminds you every month that you're giving up something objectively good. Both man and woman have to sacrifice, have to endure a little suffering, have to ... to use the technical term: mortify themselves.
We also don't use the pill, but there are other ways of spacing children, or preventing once one gets older and believes that the quiver is full. :)
All of which are contrary to the natural law, in my opinion, my wife's opinion, that of my religious leaders, and of virtually every Christian leader prior to 1930.
I really find it hard to believe that you, your wife, and "virtually every Christian leader prior to 1930" oppose breastfeeding. I didn't realize that breastfeeding was so controversial. For family planning that is truly "natural," throw out the charts and the thermometers and try Sheila Kippley's approach: