We both agree on getting the birth rate under control. When you look at developed nations, they have. Japan’s and more than a few in Europe have fallen below 2.0. One reason given for allowing immigration in those countries is because a birthrate less than two isn’t sustainable either. This is why the US has a higher birthrate, though not as high as developing nations.
India is a good model. Their birthrate was so out of control in the late 1960s that the US was considering cutting off food aid. Subsistence farmers tend to have higher birthrates because they want more children to work on farms. So one solution is to increase agricultural productivity for higher yields, and decrease the amount of manual labor done. You may disagree with that solution, but that is where GMO proponents, such as myself, are coming from. Take what did worked here, high yield farming, combine it with new innovations so it can be done safer.