My girlfriend took me on a really fun trip but I think I still want to break up with her.
What did she do that makes you want to break up with her?
While the trip was fun, I feel like I just don't want to spend time with her anymore.
It's great that you had fun on the trip and you were able to learn something about yourself. If the relationship isn't fulfilling anymore you should try to figure out why. If that doesn't help then you two probably just weren't meant to be together and breaking up makes perfect sense.
Yea breaking up does make sense
If you decide to break up with her be honest with the reason why. She may be willing to make changes necessary to keep you in her life. If not, at least you both can be on the same page and have some closure.