A good sized horse for me...would this be too big?

Well it all depends on what you can handle! For me i have to look if they would be too small because im 6ft. but i have a friend who is about your size shes 20 tho, but she rides horses that she has to get a ladder to get on to! Or back them up against a gait or something! haha she had a horse that was about 17hh!!! He was massive and she looked like a shrimp on him but she rode him like he was a pony! Like i said, it all depends on the person. You definitely don't want one that is too small! lol