i dont wanna be "that guy" but as someone who's lived in both the US and Europe...Europe is ****ing overrated man. It's nice in some of the countries, sure, but I feel like you'd get the full experience just going to someplace like Croatia or something and partying/exploring that country instead of backpacking through Europe.
once you've seen a couple of cities you've pretty much seen it all.
but whatevs man have fun on your backpackin journey. ive met americans doing the same thing.