It's very possible that I'm looking into all of this too much but I don't know. My aunt (who's a lesbian) asked my sister if I had a boyfriend. My sister said no, and then my aunt asked if I want one, and my sister said no again. Then, I was with my aunt last weekend and she was asking if my dad is very conservative and I told her yeah. She said she was sorry, kind of like joking about it. She said my grandma who is catholic and conservative is still really great with my aunts wife and is supportive of them. It seemed kind of random. Then she had pride stickers in her car and asked if I wanted one. It could all just be a coincidence, but it makes me sort of uncomfortable to think that people in my family might know (or at least suspect) and are talking about it behind my back and trying to get it out of me.
Hard to say if she knows or not - most of what you describe could have been said/done for a variety of reasons. Maybe she asked if you wanted a pride sticker because she suspects you're gay - maybe she asked just because she figured you might be supportive/friendly in the family. Who knows. She may know more the kinds of ways gay people might react in certain circumstances, but that doesn't mean she can automatically "discover" you or anybody else. Just a suggestion, but if she's also gay and, as I suspect, likely to be supportive, you could always come out to her and explain that you're not ready for the rest of the family to know. Obviously I don't know your aunt, but I would at least hope that she would be respectful of a request like this?
I've thought of telling her and asking her to not tell my family, but I feel like my sister deserves to know first. I'm not that close to my aunt and I am very close to my sister so I would feel guilty telling my aunt before my sister.