Really bad cellulite and I'm young?

True, it's not that bad, just eat good stuff and go to the gym. You need to do some exercises for your glutes (your butt muscles) and for your legs. If it so much of a problem for you can go to a dermatologist and he can maybe prescribe you some cream or else. One thing is sure, you can't fight the cellulite by doing a diet only or going only to the gym. You must do all of these things for better results. Go at least 3 times a week to the gym, eat good stuff, consult a dermatologist and you will be fine. Don't try any of that fake stuff over the internet (creams, pills ecc.) cause it won't help you. If you want to try that stuff, go to a doctor, he will know best and most importantly it won't be bad for your health.