Am I overthinking about this girl?

Hey, so I'm a confused College student at the moment and it's to do with a girl.

We share a class together and she always sits next to me (except for 1 time), we get along well, we laugh and I feel a connection with her that I don't feel with most girls. I'm not sure if it's because I feel we get along so well or something else.

In class yesterday we had to go into pairs for a task, so she (who looked amazing this week haha) asked if she could go with me, which I naturally went 'yes'. However another guy had to go with us as he was left out, I was naturally disappointed as I looked forward to one on one time outside.
So while we were doing the activity I seemed to notice she only really gave her attention to me in terms of talking, communicating, laughing, etc. Although she did ask one or two questions to the other guy and I also made attempt to talk to him which I did more so than her. I also noticed that when walking as a trio she always walked beside me, I'm not sure whether it just happened or she made sure it did.
So my question is am I looking to much into this as I have absolutely no idea when it comes to this stuff? Also this is probably nothing but while sitting next to me and I saw her in the corner of my eye playing with her hair, but stopped when I looked at her, is that anything noteworthy?

Sorry for the length but lastly, We have an assignment where we need to be in pairs go to an event together - I was going to ask her due to liking her. Anyway I was working up to asking her as I had a rough plan. Just as I was about to, it felt like I hit a brick wall and lost the opportunity to ask her, which I think she'd say yes. I'm seeing her tomorrow so any tips to make sure I don't miss the opportunity again.

Thank you for the help. Much appreciated :)

Your really over thinking :) it's really simple. She clearly has a soft spot for you otherwise she would constantly laugh with you, talk with you or even ACTUALLY ask you to be her partner. By not talking as much to the other guy she is showing you she would much rather spend time talking and interacting with you.
Hope this helped :) just talk to her properly about how you feel but don't make it sound cheesy otherwise that could erase all feelings she has for you.
Just ask her if she fancies going to the shopping centre, having a movie night, meal or even cinema! As simple as that.
And for the note: her playing with her hair and the immediately stopping is a sign meaning she most likely likes you otherwise she would just carry on. Or maybe it could even be to get your attention on her.

As a girl I can tell you two things

1. She likes you/fancies you
2. You should go for it, even if I am wrong it's better than keeping your feelings locked within