Someone please help with this girl?

Please take time to read.There is this girl who I am in love with and have been for a while.She flirted with me alot in my cl and wanted me to sit next to her all the time the problem is i ignored her and sometimes gave the impression that i did not care about which is not true, i just got nervous alot then she had to go to some tutoring program at our school ,since she thought i don't care about her i guess she decided to not talk to me anymore and i didn't work up the nerve to go up to her and talk to her ,yet when she sees me she stares at me, then i found out she got with this one guy but i don't know about them because they never hold hands or even hug ,and she does not smile alot around him ,but she still stares at me then the other day me and my friend were walking and she came up to us and started to talk to him ,and when she got there she just told me hi real quick like she was mad and kept talking to him ,then it got quiet then i started talking to her and asked her how she has been because i did not talk to her for nearly 2 months ,and right when i started talking to her she looked in my eyes and smiled the whole time as we were talking and it was a real smile i could tell ,then her boyfriend came and he didn't even hug her he just said hi and then we were all talking but the whole time she was staring at me and smiling, then we said by and she went to her next cl ,me ,my friend ,and her boyfriend have lunch that period. i was out in the courtyard and then i saw her boyfriend sitting on the bench with one arm around another girl and his other hand on her he was showing that girl more affection than his girlfriend and that pissed me off.Can someone please tell me what to do and if i have a chance with her.