Me and my girlfriend are having some arguments because she said that I'm to self-centered, I have no initiative, and I'm not so matured enough.

I am doing all the things that I can do to change myself, because I want this relationship to last long. But it seems that there is no effect.
Can you help me how to be matured enough, or just an advice will help.

You mean how to be mature, how to act in an adult fashion.

What does she say that you do that is immature? Let's start there.

The self-centered part? Start thinking of other people first and yourself (and your needs and wants) second.

I don't know, maybe because I annoy her sometimes.. maybe she thinks that I'm so childish.. :(

And with self-centered part, I already do that, I already understand that I should think my girlfriend's situation..
Our main problem now is the immature thing..

By the way, we are cool off now. :((

If you're changing yourself to make the relationship work maybe it wasn't meant to be. Compromise is one thing ,but you do not need to change who you are.

How old are you?

How long have you two been dating?

What issues does she have exactly? Has she given you examples on how you act immature?

The thing is, you shouldn't have to change yourself for someone else. Not that I'm saying you should be selfish, or act immature, but as your girlfriend she should accept you for who you are, or leave.

It sounds to me like she's on the edge of leaving, and she's putting down her case against you so that it won't be a complete shock when she breaks up with you.

The only person you should change for is yourself. Better yourself because that's what you want to do. Don't do it for someone else, that never works.

I'm 15 years old.
For about 5 months..

She said that I always want to be with her all the time..