WTH SHOULD I DO...OMFg!?

Alright, my situation is really basic to majority of you people. I am a sopre and the girl I like is also a sopre. The girl I like is name Stacy and she already knows that I like her for like a month now. In the beggining after she found out that I liked her, she kind of showed some sign that she wasnt interested and showed some sign that she was. But as time gradually progressed, she has shown a lot of sign that she liked me ... Like yesterday during PE, I hang out with a group of people and she hang out with her group. So as I was talking to my friends, she was really near me and I kind of got this vibe i guess(: And today after school, i was walking from my cl to the place where I chill with my homies, and when i turned around, I saw her and her friend giggling as Stacy was near me. I kind of felt like she wanted to ask me to sadies since today was sadies, which i have a date btw [not her]. so i keep telling myself that she is going to say yes when i ask her but im scared