Need advice in approaching this girl

So I've liked this girl for 2 years, think she liked/likes me back, or finds me attractive atleast. I started college and I noticed her there too last semester, made a bunch of eye contact but I never acted on it. She held it usually while I would shy away. Only talked to her like 5 times in junior year and appeared happy when someone told her I wanted her number but she had a boyfriend so I said I didn't ask for it. Pretty sure she heard the rumor that I liked her back then anyway.

Now I've only seen her twice this semester, first time was when I was with a friend and I think she was late to class, only noticed each other 2 feet from each other and as soon as our eyes connected she looked away, she looked like she was in a rush late to class or something and I was with a friend at the time.

Now I saw her today, told myself I'd spark a convo then was caught off guard by her friend that was walking with her. idk if she noticed me but her friend Def did. they were laughing at something at first then both got quiet and started talking in a really low tone.

My only issue is, she's the first girl I've ever actually liked a lot, same religion/culture and shit. pretty sure she's into me but I don't know what to do. idk if I should ask for her number the first time I approach, or just introduce and say hi every once in a while whenever I see her, can make it every Wednesday but she'll always be with friend... 4 weeks into semester and I've seen her only once and I really want to do something before this semester ends and I feel as if time is of the essence.

tldr: like girl, dunno if I should try to approach in front of her friend who may, MAY, also find me attractive idk I'm new to this shit. I dunno if asking for number after talking for the first time is the right thing or just introduce and hope to find her alone some time. sorry for long text but pls any advice would be great, never done this before and we're both 18 in college. dunno if I should be worried I barely see her or wait a few more weeks for semester to settle. could also ask friend who says hi to her here and there say something but I dunno