You are definitely not alone. I think more and more teenagers are doing this now...eating unhealthily or too much. Life is stressful, your hormones are a little out of whack and there's a lot to do and be anxious about.
I used to do the same thing. I would come straight home from school and eat pretty much until I went to bed. I don't remember ever being actually hungry, I just wanted to eat...frozen pizza, soda, ice cream, lots of bread, pudding, string cheese, etc. I think for me, it was the lack of structure in my life. I would have NEVER done that at my dads house, but my mom was never home and bought us lots of food that was quick to make and pretty unhealthy.
It's easier now because I have such a routine. Routines are important. When our hands are busy and are minds occupied, we are definitely less likely to eat out of boredeom. And try to think about what you're going to eat in advance. You're a little less likely to eat something unhealthy if you've been telling yourself all day that you'll have a healthy snack instead.
But a lot of it does come right down to will power and getting in the right mind set. Eating habits are hard to change, but little changes add up and help.
Good luck, I have all the confidence that you can get on track and start making some healthy changes for yourself!