If you could write a note to your younger self, what would you say in only three words?
I had two thoughts. 1) Words can hurt. 2) Try your best.
What would your note say? 
Enjoy each day
following that thought
Family come first
Love yourself first.
It's easy to think that if you love others, they will provide you love you back. Ultimate compassion comes from loving yourself so others don't have to, then you can love them unconditionally. Love is a gift not a requirement.
I would send " love yourself first" or "calm down girl" ...
Happiness > GPA
Be yourself and fuck others who think you are not good enough. No one can bring you down, stay strong baby girl.
It would be STOP BEING AN A**HOLE
You do not need a man's approval to feel like you are worth something. And stay away from guys named Chris, Jeremy or Rob they will only cause you heartache.
Pay her attention.
Me 4 years-ago would've used this advice quite well.
@Shinigamipwnage1
Don't give up
It gets better.