Am I wrong for thinking it was okay because I was underage and couldn't drink?
What makes you say it was ok because you were underage?
If I had been able to drink I would have gotten drunk and been criminally liable.
It is a bad idea to put yourself in situations that could become criminal, especially if you are underage. It is good to refrain from drinking if you are underage, but you should stay away from dangerous situations where you could get into trouble or be injured. You should practice moderation and wisdom in your actions.
I'm practically an adult and acting responsibly. Why limit my freedom.
It seemed in the past situation, being underage is the only think that kept you from getting into trouble. Use that as a learning experience to be mindful of the situations that you can put yourself in.