I am 5'5'', would a 55cm frame be way too big for me?

that sounds big. I'm 5'5" and was more comfortable on a 49cm over a 52cm.

pretty sure it is. I'm almost 5'8" and I ride around on a 53cm frame. Visit your LBS and let them help you out.

It depends on a lot of things, and on what you care about. If you always stop the bike is such a way that you won't have hard crotch contact, then you can get a bike with a standover height as tall as your cycling inseam plus shoe thickness. In this case, a 55cm seat tube combined with a small bottom bracket height and a slack seat tube angle might work well for you. Height isn't the be-all end-all criterion.

Road Fan

Yes thats tooo big the rule of thumb is frame size should be 2/3 of your true inseam for a road bike