The ultrasound was abnormal—you still have small kidneys. They are growing, but it sounds like not quite enough to keep up long term. One kidney (left?) was 3.7 cm at birth and is now 5.1 cm. The other (right? I can’t remember) was 3.9cm and is now 4.9cm.
The good news is that your labs came back normal, meaning you have plenty of function for now.
So fiddle-dee-dee. We will think about that next year--at your follow-up.