Been there, done that. I felt more like I was "raking it in big-time," not just "doing pretty well." But that's subjective.
and we would like to have children. Should we wait just because she's in the military?
YES!
How is that fair?
She volunteered and she is being paid. If she can't do her job, she should get out. If she plans on not being able to do her job when the hard part rolls around, she should get out NOW.
Men in the military don't have to wait to start a family
My wife got out while pregnant with our first-born (her first enlistment was up.) I have been fortunate enough to be there for the birth of all of my kids, but there were no guarantees. Number 6 (six) (yes, that's right, s-i-x) is due in Dec - I'd say it's slightly better than 50-50 that I'll be home for this one. Again, there are no guarantees. And that is the key difference - men with pregnant wives can deploy. Pregnant women can't.