I would encourage getting your vitamin D levels checked as one part of the overall plan. I also make sure I take a good calcium supplement *with* magnesium. And from what I've read you actually need MORE magnesium than calcium--the best plan (from what I've read) is to slowly increase your magnesium until your stools get a little loose and then back down a smidge from that amount
I also use xylitol (gum but even more regularly in my toothpaste).
I'm seeing great improvements in my oldest's teeth that were getting weak with growth spurts.