Charlotte Mason was British, so she would have concentrated on British and European History, with American in the mix. However, IMO, you’d want to concentrate heaviest on American, then British, then World. How you do it is up to you.
You’re in a specific season, with your babies. If you can’t make your ideal CM education, don’t beat yourself up over it. Use what works for your children and, most importantly, you. If you don’t consider yourself and what you can reasonably do, you’ll all suffer.