I wish it were 18 years down the line you realized you lost yourself and you at least have 18 years you savored but lets be real. Our kids will start school and what will you do with your time then? Stick yourself in their lives and become a nuisance? I think you can become depressed at having no identity of your own.
According to the healthline webpage 1 in 10 women get depressed weeks following giving birth. Half of adults don't talk to a doctor about this, I think it is much worse for moms who take on the task of their children. They immerse themselves so much in their children they may temporarily forget this issue but rather than fixing it they help it fester like a fungus.
Let's say you don't suffer from depression, would you want your child to be one dimensional and not have any other interests? So, why should your life only revolve around your kids? Join a quilting group, (yes, people still do that), sewing, running, cycling, knitting, writing, book clubs, anything just have a hobby, group you meet to engage in outside of your children. Leave the kids at home, breathe, take a one hour vacation a week with your spouse and occasionally alone.
Live to show them how to live!