Yeah it's odd when you look back at your own work. Some filmmakers don't look back at their work at all. I look at my work a lot actually. I feel like I learned something while looking at stuff I've done in terms of what I'm going to do in the future mistakes I've made and things at work or what have you.
I would tell 17-year-olds to be proud of who you are. Don't try to change yourself for others. Focus on school and your future. Boys and friends will come and go just focus on you and your future.