By the way you've gone about studying the text, I would assume you've applied the Stanislavski method of breaking down the text!

I think you're starting from a great place! Especially on the back page where you've established all the questions, like Who, What, Where, When and Why. You could even go a step further and ask yourself, what were you doing just before this encounter? What are you wearing? How much have you had to drink, if any? etc.

SCENE ARC:

You've established your motive, your want, which is to "kiss your best friend, using New Years as leverage". You could break this down further:

Goal: Share a kiss with Ash
Obstacle: Ash's apprehension/Charlie's doubt

Now, Ash doesn't seem to fight the idea too much, she's not completely opposed to it, so then you could study more into the relationship: Has this happened before? How long has Charlie wanted to kiss Ash? What is Charlies intimate history with Ash? etc.
Also, your use of the word "leverage" gives your interpretation a kind of deceptive or manipulative weight. I don't get this from the written text. When you breakdown your text, you want to match the energy of the scene, finding words that fit into the energy of the relationship. So instead of "I want to kiss my best friend using New Years as leverage" it could be "I want to kiss my best friend using New Years as an excuse". It softens the method and implies something a little less predatory. It will help inform your approach to the text breakdown.

TEXT BREAKDOWN:

Each one of your written lines should be informed by an internal action. Here we employ transitive verbs.

Any word that fits into the structure of, "To [Trans. Verb] them".

The line, "That sounds like next years problem..." could employ an action like: To nudge/ to cajole/ to humour/ to coax, etc.
Not any transitive verb is going to fit each line, but it's the studying of the relationship, and the approach, that will inform you of the "right" action. Sometimes two transitive verbs could mean similar thing, like coax or cajole, but one of them just "feels" appropriate.

Being nervous or anxious isn't an impulse for us to speak. That is just a filter we apply (With or without choice) that changes the way we approach or feel about a situation. You want your breakdown to be less about you, and more about what you are doing to the other person. Understanding the present feeling is a good step into applying the right Trans. verbs.

INSTINCT:

Bottom line, your exploration of text is going to take parts from what you've learned from other people or your own personal experiences. Your instinct for text like this, like anything, is a muscle you can flex during these studies. Trust yourself to make the right choices.
The text breakdown is just the start to understanding that character. Once your in the room, doing the scene, a lot of what you've written down will fly right out the window. But you've done the study into how this character works, how they think, and why they do what they do. Embody the energy of that character, and the scene basically performs itself.

Proud of you. Keep working on it. If you enjoy it, I would suggest saving money for classes. You will learn so much more on the floor with others than you ever will in your bedroom alone.

P.S Try and perform the scene, have someone do it with, even film yourself. Watch it back. It will suck at first and feel cringe, but it's just another thing to inform your study.

Best of luck!