I dont think anyone here is going to tell you to stop growing because she said to. we all know how enjoyable and rewarding the hobby is.
the main point here is one that transsends this issue: nobody can TELL you what to do. its that simple. if you're just 'dating' someone and they TELL you to stop doing something because that's the right decisions for THEM, what else will they TELL you to do in the future?
you are standing at a precipice, right now. you are an adult and you want something in your life. it's your decision, not hers. weigh her feelings on the matter, especially if you live together, but the choice is yours.
ultimately, no one can TELL anyone what to do. its not about the thing, its about accepting the other person for who they are. THE CHOICE TO GROW IS YOURS. if she chooses to leave you over this, its important to realize that THE CHOICE TO LEAVE IS HERS. but DO NOT accept an ultimatum. its essentially giving her cart blanch to make demands of you using threats.
i would NEVER let anyone control me like that. also, remember that keeping a cool head in your conversation with her over this, while not giving in inch for what you want out of life to be happy, will show her some real balls. women crave that in a man, even if the disagree with you.