The guy who taught me my job was the overly critical type, when I confronted him on it he said that whatever he wasn't commenting on was good. Whatever criticism he gave became more and more fine tuning, and I could assume everything else was in good shape. I learned a lot, and could appreciate being held to the highest standards (higher than his sometimes)... On the other hand it was stressful for me and I wound up hating the guy.
I'd like to stress having high standards - I think it really makes a difference for a student to be held to high standards early on, it's the kind of thing that sticks.
My piano teacher is a little on the complementary side. It's nice and all, but I know when I've botched and often the compliments seem to be intended to comfort. The best compliments are kind of accidental, like when a teacher shows faith in the students abilities in some offhand way, it's more genuine. Likewise, the most flattering compliments are from those who rarely give them.
Afamee, you should bring it up to your teacher that it's bothering you. At least give her a chance to know that things aren't right. It could be her fault, yours or both (usually things are a bit of both), but the only way to make it right is to talk it out - at least to try... Then if things are still difficult, your teacher can at least know why you quit.
It's just not fair to leave someone not knowing what hit them. You'll never know what issues could be resolved unless you bring it up.