Should I make a move?

So there is a girl, my bestie. I know her for two and a half year now and I’m really into her, what she probably realized but Im not sure tho. We talk a lot, meet in the city, have lunch sometimes, go to parties, etc. Otherwise she is my classmate so I see her pretty often. When we started our friendship she dumped her bf, lets call him Josh. But at that time we did not talk a lot, so I could do nothing there. So she got a new bf who’s name is Steve(not literally). Time passed, and their relationship broke, but I did not asked her out then(I do regret it, but never mind now). They gave their relationship an other try which was not viable. It lasted for about two weeks or so. Simultaneously she got back together with Josh, what I don’t understand because when they split up her heart was broken. Now they’ve been together for 6 months, and we still talk very often, although I am not sleeping at her place that much anymore. Every time we speak she comes up with her boyfriend if they have an argument or just shows me what she got from him and this frustrates me. Recent days I was thinking what would happen if I tell her my feelings. Maybe I should wait maybe they will split up, I don’t know. If she rejects me I can take it, but not if she wont talk to me later on because of it.

Thoughts?