I’m 5’3’’ and I have small. I have tried medium, but liked the look and weight of small better. I don’t even fill the small up. I think medium can look overwhelming on small frames. Best to try if you have an option to do so.
I'm 5' 3" and also chose the small. IMO, your actual bag size needs are more important than matching the size to your height. However, in terms of aesthetics, Medium was just on the fringe of being too big on me. If you're 4' 9" you should definitely try on the Medium before buying it.
I’m 5’2 and the medium is a little big on me but I don’t mind it since the capacity is great when I need to carry more. It’s also nice to have a larger Chanel as an option because my entire collection is flap bags