How do you know if you are friends with someone?

So I recently met a colleague and we have a lot of similar interests and when we have talked at work we have gotten on really well. We have spoken on discord and I she is planning to join a Baulders gate game with me and some of my friends. She asked if that would be alright and me and my friends agreed. We have spoken via online messages a few times outside of work and I think that it would be good to be friends with her. I don't have many friends honestly and having one more would be great. I have been fairly open in talking about stuff like myself as I just feel comfortable talking to her.

But I was just wondering how do you know if your friends with someone or if they want to be friends with someone?

Does it sound weird to want to be friends with someone?

I could really use some help with this if that isn't to much trouble.
How do you know if you are friends with someone?
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