Re: I know I don't know what to do
Have you tried talking to her about it? If so, what was her response? However, if I had to take a guess, I'd say you never brought up the subject.
What with hindsight being 20/20 vision, this is something that you should have discussed before moving in with each other. After all, you said it bothered you then.
Well, anyway...Here's what I suggest --- Wait until a time when you're both in a calm mood, then bring up the subject. Say something like, "When you say this and when you say that, it makes me feel hurt and unloved." Then say, "How can we go about improving this situation?"
As you pointed out, I think many of us when we were young and immature would say "I told you so." or would correct other people. When one is immature, one has yet to develop empathy. With most people, this quality comes with age and experience. However, some people seem to have arrested development.
Is she much younger than you are? That may be the reason that you are more mature in behavior. If you're about the same age then she needs to grow up.
See where things go when you bring up the subject. Her reaction and response will tell you a lot. If she is genuinely surprised in the sense that she didn't realize that she comes off that way and expresses an interest in changing her ways, then that is a good sign. If she gets angry and reflects this back on you---not a good sign.
Does she behave this way with other people? If so, has anybody said anything to you (or her) about it? She needs to be aware that such behavior is obnoxious and that others will think of her as a know-it-all.
If you don't make any headway with this problem, then you have two options: 1) You both could go into couples counseling (if she is agreeable); or 2) You can just move on. Good luck with everything!