I went into Undertale completely blind and played a couple of hours before I realized you could get through every encounter without killing anything. I kind of gave up after that because I felt so bad.
It's actually an important mechanic. How you play changes the game's ending and you get a chance to try again. It's meant to be played several times different ways, so you didn't do anything wrong. :)
Yeah, agreed. Even if you complete a full run with some kills, if you then replay as pacifist it will a) go a lot faster and b) a heck of a lot changes.
I think it's actually meant to have 1 playthrough middling and then 1 playthrough pacifist, partly because of the way the Toriel fight tries to trick you. Partly for this reason I don't like telling people to play pacifistically out the gate, even though apparently this can backfire.
A couple of hours is not that far in. I would strongly recommend that you restart and play a pacifist run because that leads to the best, most comprehensive ending.