Something happens between the time your kids are in 1st and 2nd grade and high school. Life ZOOMS forward at a pace you never knew possible, and never anticipated. You get so immersed in life with children you don't have time for much else. The school days, soccer practices, dance recitals, swim meets, scout meetings, piano lessons and practice, band, chorus, church, playdates, birthday parties, PTA meetings, carnivals, tournaments, camps, field trips, hair cuts, dentist and doctor appointments, clothes shopping, baking, cooking, etc etc consume you until you look up and they are almost grown. I have so many moms of teenagers who come to me and confess with so much needless guilt that the last family pictures they had were when their children were toddlers. They feel bad about it and are determined to make up for lost time.
Ditch the guilt! I'm 100% sure those years are documented on your phone and computer (don't forget to print them - seriously). It's never too late for family portraits. Do what you can when you can, and that is all you can do. That is more than enough.