Dear Christina,  

Even if you are living a perfect Christian life now, your life would change in a fundamental way if you became a nun, because, when you did, you would offer yourself to God (in answer to his call) in a total way by taking public vows of poverty, chastity and obedience, becoming his Bride. You would be set apart for him, dedicated exclusively to his love, and be a sign for others.  

And then you would make other changes to take care of and protect your call: more prayer, a community life, dedication to apostolate, voluntary renouncing of many good and 'normal' things you may do now. 

God bless.