So, you're an example of the worst of both worlds.
Regardless of whatever small accommodations you may make, you apparently consume at a first-world level, because "all doing our part" seems to indicate that you're not doing a lot more than those around you, and for the most part we're not doing much. Presumably you want your kids to be able to do the same. You definitely don't sound like you're talking about slashing your or their consumption by say a factor of 5 or 10.
But you also want to have "a few" kids, which usually means 3 or more, which means above replacement level.
You're not just increasing the number of people; you're increasing specifically the number of high consumers.
You can't have both increasing population and increasing per-capita consumption. In fact, you can't get away with increasing either one for the long term without at least reducing the other. And in the still-longer-but-not-that-long term, there's a floor on how far you can reduce consumption and still stay alive.
So at some point you HAVE to stop increasing the population. Or not only does the surrounding world suck, but people simply start starving.
... and people who think the "demographic transition" is going to ride in and save the day are thinking pretty wishfully. It may cause a bobble. It might even get the world 100 years. But in the end, evolution keeps running. There's going to be a heritable tendency to overcome the "demographic transition" factors and reproduce anyway. If that's not artificially stopped, there's going to be a problem.
Space travel is not going to fix this either.
I'm sorry that reality seems anti-human to you, but then the universe has never been obligated to care about humans.