Unable to handle my girlfriend annoying behavior ?

Hi ! I am a 21 years old guy and i m in relationship from over 6 months with a 18 years old girl. She love me so much and she purpose me first. I also love her truly b't the problem is that she is too possessive to me. And she don't even trust me properly. We love each other so much b't there is just a week point in our relationship that is understanding and her annoying behavior. I work somewhere and unable to give her time. I have already told her this b't she is too much stubborn. She is too childish which i love on her nature b't sometimes it's become a serious problem to me. I just want to know that how should i handle her angry and stubborn behavior ? We fight 3 or 4 times in week just cause of her stubborn and angry behavior. So plz tell what should i do with her ? I don't want to loose her I love her so much and I know that she also love me so much.

HI Jay!!!

I can understand your problem Jay... Girls tend to behave like this in this Age and she is only 18 years of age .. With time she will grow and will be a more matured human being....

Try to make her understand that her love is now affecting your professional life and annoying you....
I am sure that she will understand your view point and will stop behaving in this manner....

I have already tried this dude ! B't after this she start talking to me rudely and answered my questions very rudely ! Dat's y m so confused ! I don't how to make her understand ! may be u right dat her age is the big reason for her this kind of behavior ! I think i have to give her time to understand me !