With regard to struggling on six figures, I think the tricky thing is that raising a family requires pretty much all available resources, no matter how many resources you have. So, up to a very high income level, there’s always going to be something you can’t afford to give your kids–a lesson or camp not done, a trip not taken, etc. There are almost always going to be choices and tradeoffs. And that applies to time as well as money–there will have to be prioritization of needs. If one child needs speech therapy for the spring, another may not be able to do a sport, and so forth.
More practically, I would very much suggest not letting yourself be well below the median income in your area. As long as you are median income, life is generally OK, but if you’re living on $40k in an area where the median is $80k, you’re going to be suffering. In that case, it’s important to either move or make more. Also, housing costs have to be watched carefully. If housing costs are anything near 50% of income, it’s going to be painful. Try to keep housing to 25% of income or lower. The lower you keep your housing costs as a percentage of income, the easier your life will be.
Also, the better your financial situation is when you get married and start a family, the less income you’ll need going forward. If, for instance, you had no debt and were able to pay off a house before having children, your income needs would be dramatically lower. And having a paid off house is actually not a ridiculous goal to have if you are a 20-something living in a low-cost area. It can take a long time to find the right person, but if you use your time wisely, it won’t be wasted.
I suggest reading the following books:
The Millionaire Next Door (it’s about how moderate income people like teachers are quite capable of zealously saving and actually outpacing higher earners)
Total Money Makeover (that’s Dave Ramsey’s book that teaches the Baby Steps)
daveramsey.com/new/baby-steps/
Elizabeth Warren’s All Your Worth budget (50% fixed expenses, 30% wants, 20% savings and debt reduction) is a great target. I would personally find it a headache with our complicated family expenses (we have somewhere between 30 and 40 categories), but I think the 50/30/20 plan could work very well for a lower income person or a younger person.