At what age does your feet stop growing?

Ok. so my left foot is almost half a sizer smaller than my right. i went into david jones the other day and got these really expensive nice shoes. being in a rush, i tried the shoe on with the left foot. and bought them. i just put them on for the first time and it hurts my right foot! it's OK though. the left foot is very comfortable, and fits well. when do feet stop growing? i'm 16 ! i hope theyve stopped, these shoes were so expensive