I think, in this case, yeah, I'd ask her. Consider the evidence - she's already posted things about being a lesbian, she can't really be surprised if you ask her straight out if that's a real thing. I think the challenge (particularly for us on the spectrum) is coming off as curious instead of judgmental about it.
I think how I'd do it is just ask her like: "Hey, I saw all the LGBT stuff on your page. Are you really a member of the community or an ally? Just curious." or something like that.
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Your neurodiverse (Aspie) score: 175 of 200
Your neurotypical (non-autistic) score: 49 of 200
You are very likely neurodiverse (Aspie)