When My Kids Outgrow Me

I feel so small sometimes when I see my kids outgrowing the clothes and toys I bought them for years. Last week, their old school desks barely fit my now-taller daughter, who's only 10! She asked me to help her pick out books at eye level with a grown-up rack in the library for the first time today. It's cute when she calls me 'Mommy,' but part of me wants them to grow up and be independent, another part worries I'm missing their childhood without even realizing it. Am I just being dramatic, or is this normal? How do other parents cope with watching their kids get older so fast?