There's this girl in school!?

There's this girl in school I really find attractive, she always stares at me and smiles. My friend even notices her smiling and giggling everything she sees me. Everytime we see her alone my friend points at me and she starts smiling, getting red and giggling. During passing period going to 2nd period I stand outside my second period class and chill with my friends until the Bell rings, she passes by there everyday and she always stares & smiles at me but for like 2-3 seconds . Bad thing is she has a boyfriend, but it's an off and on thing. She started going out with him again on Friday but when she passes by my 2nd period with her boyfriend she still smiles and stares at me. Today I went two classes down to talk to my friend and I saw her pass by with her boyfriend. She was looking around and and she even looked back, my guess was to look for me. I have her on Instagram and she likes my pictures.i messaged her before to tell her that she shouldn't mind my friend always pointing at me when she looks and the conversation ended good but that was when she was single. & today while me and my friend were going to 6th period we passes by each other and she saw me and my friend and she let out a loud giggle like super loud while her boyfriend was right next to her. My friend was like dayum that was loud. Should I message her again? Should I talk to her in person? What should I do? I have a huge crush on her. Do you think she has a crush on me?