Most people think that if you cant stand flat footed over the frame it is too big. I dont believe this to be true for a person with a lot of riding experience. For me a frame is only too big if the seat is all the way down and your knee isnt slightly bent when extended.

On a road bike i put one foot on the left pedal push off and swing my foot over the top bar,,so why would I care if i cant stand straight up with 2 inches clearance from my crotch?

If you are true novice,,,you might not be able to ride a frame like that. I have ridden 25 inch frames often and am only 5' 9. I ride a fxie now that has a 58 cm frame,,,and I love it, I have a slightly shorter one but it doesnt feel as comfortable as the larger frame.

I dont think 63 cm is too big for you, if you are comfortable on it, go for it. Smaller frames make me feel cramped and strained.