Can't seem to get her out of my head. What's my issue?

In advance, thanks to anyone who can help me understand what I'm going through.

There's this one girl who I see everywhere I go, mostly at school (I'm a senior, I'm not sure if she's a freshman or sophomore). She haunts my thoughts. Every day, she's all I think about. It's impossible NOT to think about. Usually it's planning how Id like to introduce myself to her (which I've put off for quite some time, I'm not confident that it'd end well in my favor). In class I just sit there and think. I barely get anything done. I'm actually losing sleep over this girl, and I don't even know her name.

Has anyone else been in this situation? I know I'm young, so my emotions are still raw. I don't have a history of having somebody I can say that I love, so maybe I just feel like that's what I need and she's the one. Or something along those lines, I have no idea.

Thanks for taking the time to read this. Apologies for any gramatical errors, emotions and typing on an iPhone don't mix well.

Love

It's quiet obvious that you're falling for this girl, from what I've read you haven't even spoken to her or even know her name which is bad because you won't ever get over it, it's easier then it looks trust me, go talk to her introduce yourself to her the more confident you are the less awkward silences, if you're really shy bring a friend with you and he could talk to her friends you know? It will all run smoothly! Good luck! (Make sure you smell good if you speak to her haha)

Just try your best to get her out of your head