You may have thought a booster was going to eventually be needed but the general public wasn't pitched the idea. The vaccine schedule (2 doses for Pfizer/Moderna, 1 for JJ) was sold as the ticket to backyard freedom. While the development of the vaccines(s) was impressive, the messaging and politization of the product left a lot to be desired. It's a very useful tool to manage the disease, but it's not the only one.
As far as your kid's vaccination, pediatric vaccination is based on a vaccine schedule. Boosters and vaccine schedules are fundamentally different. Generally speaking, live vaccines don't need boosters. And if given a booster, the timing is well beyond the 6-8 months that's been proposed for the covid vaccine.
As far as covid boosters are concerned, there is much disagreement as to who gets a booster, when, etc. There isn't enough safety data available for the CDC/FDA to make a blanket approval.