I would say your chances are pretty good if she's that tall already. My colt was 14.3 at 11 mos. Old and has ended up almost 18 hds. He's a draft cross, no idea how tall his mother was, father is about 17.2.
Oh, I forgot to mention 2 ways that are "supposed" to tell you how tall they'll end up. Measure from the dent in the front of her knee down to her coronet band. If it's 16 inches, that translates to 16 hands. This worked with my colt. The other way is to take a 4-5 foot piece of string and measure from her elbow to the point of her pastern joint. Hold the string against her elbow and rotate the string from her pastern measurement point up over her withers. This is supposed to indicate her mature height..