Is my girlfriend cheating on me?

So I been dating this girl and she’s betrayed me before. But this shared her work page and tagged it and said “ make MY girl your real estate agent” what does “ my girl” mean I just feel like that means romantic but maybe I’m wrong. Once my girlfriend called her bae once and told me she got her a birthday present once. Another time she posted this entertainment thing where Anonymous people write random messages and she answers them and one of them was this person asking about the girl, and she replied that She’s an amazing person and she will do great things so, what does “ my girl” mean

Is my girlfriend cheating on me?
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