In the range 50-54 cm.
Go to your local bike shop and try some on. Stand over the top tube. Should be about an inch of clearance between the bar and your crotch.
Have them adjust the saddle height for you. Ride it for a few minutes. Pay attention to your position in the drops. Are you reasonably comfortable?
You're probably still growing and may want to consider getting a size bigger than your need right now. Grow into it.