You're young, you're carefree, you have your whole life ahead of you.
So I'm here to give you some advice on how to make it easier.
Don't take people for granted. You may think your best friend will always be there, up the road but they wont always be there, nor will you.
Remember to say "I Love You" to the people that matter. You will probably be embarrassed, but tell your mum and dad you love them, because they love you so much, more than you will ever know. You are their world. Three words from you, will make their whole day.
Don't let people manipulate you, if it feels wrong, then it probably is. Do not stay with that guy who makes you feel like shit, for fear of being alone. Better alone and happy than in an awful relationship. You're worth so much more than an asshole who mistreats you.
Study. Please for the love of god, study. It is necessary. You can't coast by on the bare minimum your whole life. Hard work and dedication make dreams come true in the long run.
Talk about your problems. Reach out. Take it from me, bottling it up will be the undoing of you.