three months old

Last Sunday she was three months old. People always ask how old she is, and I never know if I should say "fourteen weeks" or "three months." She's a week older than three months, but fourteen weeks is so confusing, and it only gets worse as she gets older. When she's 6 and a half years old should I go around saying she's seventy-eight months old? We were discussing today at what point do you stop saying "X weeks" and just refer to months and eventually years. Puzzling.......

So speaking of three months, each month on her "birthday" we've taken a picture in the same chair, and will continue to do that every month this year, and then we'll probably start doing it every year on her birthday after that. So look at the pictures from the first three months. Isn't it amazing how much she's grown??? (The top two pictures are months 1 and 3, and the bottom picture is two months) Notice that her facial expression hasn't changed much......