Is it wrong of me to  tell my gf she is immature for saying I don't consider her feelings?
What would that tell the other person apart from simply stating an opinion?
If the person is being told by their boyfriend they are immature, it means he finds them not mature enough.
You should ask for a thorough explanation about you being inconsiderate. If she has valid points, learn from it and try to change.
And if I don't find her apologies good enough I am going to dump her ass.
If your girlfriend stated that you don't consider her feelings, it's likely because she doesn't feel that you listen or respect her. By calling her immature, you are making her point. Instead, you should take the time to consider what she needs from you.