I am not sure where you are measuring... high up at the widest part, or down lower towards your knee?
I measured mine just for reference, although I am much taller at 5'7". The widest part of my thigh, way up at the top, is 19 inches. If you go down to about 6 inches above my knee I am 16 inches. Your measurement doesn't sound bad either way.
The only advice I would have regarding wearing shorts is just not to wear shorts that stop at the widest point of your thigh... that tends to exaggerate the size of that area.