anxiety ruining my chances

There's this girl in my Uni that i really like. We talked in the first day when she sat next to me in class, the next two days we only saw each other a few times, but didn't sit near each other. I didn't bother trying to talk to her out of fear of looking needy or creepy. I saw her in class, and she was sitting in some seats, making it seem like she wanted me to sit next to her. But i noticed my mates sitting and decided to go and sit with them last second. Now i feel like she may think im not interested or am rude because i messed up twice. I ignored her because of my dumb anxiety issue. i actually have a crush for her and she's showing signs that she's interested in me, but im always afraid to make a move. I don't know how and what i can do about this and how i can get the balls to actually talk to her more. She always sits and hangs around with her friend as well. Any advice?