Katie Holmes' only child, who she share with ex-husband Tom Cruise ... when she turns 18 on the 18th, followed by another transition several months later. That's because Suri will be leaving ...

Suri Cruise is counting down the days until adulthood, as the teenager turns 18 on April 18 ... where she has grown up since childhood. However, the 17-year-old's life has changed quite a lot ...