Thinking about confessing after 3 years

There’s a girl I’ve had a crush on since the end of 2022 when I was in 7th grade. We were in the same school back then. I followed her on Instagram and started having a crush on her, which gradually became deeper. I thought I might try to talk to her or make a move in 8th grade in 2023, since the year was ending, and I told myself I would. Unfortunately, she changed schools.

After following her on Instagram, I casually messaged her and we had a normal conversation for a while. But after a few messages, she ignored me, and that was the last conversation we had. A year later, in 2024, she wished me a happy birthday, but I didn’t reach out to her then.

Throughout this time, I’ve occasionally liked her stories to give hints, though that definitely didn’t work the way I hoped, and I don’t think she ever saw them as hints. She usually likes my stories too not much as i do, so I just think she doesn’t find me unattractive—it’s not about me being completely unnoticed, but she doesn’t seem to pick up on the signals I’ve tried to give.

I’m 17 now, and my school life ended. All this time, I never thought about confessing because I was afraid of rejection, overthought everything, and wasn’t sure what would happen if she was interested. I also wasn’t prepared to start dating since my social life isn’t great yet, though I’m working on improving it. For the past three years, I’ve been thinking about her, and now I feel like it’s finally the right time to confess.

I need advice on how to confess, what I can say, and what to do afterward if she’s interested in me.