There's a few things I can suggest..

1 - meet somewhere away from home where you already know you've come to this place (park, coffee shop, wherever you feel comfortable) in order to talk, and write down some bullet points so you make sure you talk about everything.

2 - Write a letter! I sometimes find it hard to keep straight to the point when I talk and then later feel like something isn't fully resolved, so writing a letter can make sure it is all out and then she can reply to each point. Either in letter or in person.

3 - Remember that you are both going through a lot of changes and finding out who you will be as an adult tight about now, so maybe take the time to look within yourself first. She isn't responsible for your happiness, yes she adds to it but she isn't your only source. Try to write down why you feel this way, is it because she's found her passion and you haven't yet, your routine has changed, you're feeling worried she cares about you less, etc. Try to look within yourself first and be brutally honest with yourself, then afterwards you can go to her and say I've felt this way, I think it's because of that...and if you can help me by, sending me a text every now and then or keep me in the loop of your writings I will feel more loved.

4 - read The five love languages, honestly, it's a great way to discover how you feel and perceive love. We all love differently and knowing yourself first will help with any relationships you have. It could also help you see what you feel you need and are lacking now that she is focused on that, she's not psychic so being able to communicate what it is you need will help a lot.

Good luck!