"In this case, it is not so much about capturing how the child changes over the years, but about capturing how much the child changes us, instantly, unknowingly, and effortlessly"

Perhaps that will be the case then too...and in an instant, whatever concerns you have about getting through the session will evaporate. You are an extraordinary photographer and deeply empathetic woman. I can't help but believe the results and the process will be extraordinary as well.