Why Would The Wrist Be Very Small With Mild Pain?

I am 23 years old female. My wrists appear extra small and look like a small child's wrists. I just put a measuring tape around my wrists and each wrist is 14 cm in circumference. Sometimes there occurs a mild pain in the wrists. This pain does not occur all the time, it comes and goes, and it does not depend on rest or physical exertion. However, sometimes apart from the pain that happens by itself, when i bend my wrist to support the weight of my head by my hand, there some pain occurs in the wrist and it feels weak. Other joints of my body are normal in size.