I want a 9 to 15 year old girlfriend
That's messed up, why do you want an underaged girlfriend?
That's the kind of gf I want...
If you are an adult, you do not want to be with a girl that is underage. Having a romantic relationship with a minor is not only against the law, but also morally wrong to do.
What's moral has nothing to do with anything? Get real. I can get anyone I want even if it is illegal.
You're actively going to hurt that child's development and you will also end up in jail so it is very problematic for you to go and date a child. I do hope you don't act on your desires and try to get help to see how you can better yourself and see how you can be a more productive member of society.