they make medium for a reason. youre 5'5". unless you want to look like a little girl in her sunday dress skiing down the mountain, id stick with the medium. im almost 6 foot and got a large. it wont be massive but i think it will be just the right amount of length
You realize that because you're questioning yourself so much now you're going to regret getting the smaller size just because you could've gotten a bigger one. Large will be fine if you want it to fit big. My friends medium saga fits relatively normal on him and he's around 5'5-5'6. Get the bigger size or you'll regret it later.
"To me, skiing is anything you do with skis on your feet..."-Will Wesson