Attracted to a Lovely Woman but Not Sure About Orientation

I'm a woman who's been having bi/lesbian inclinations for about a year, but have been hesitant to explore my feelings in real life. I think this is partly or even mostly because I'm attracted to people when I get to know them; internet dating has never worked for me and I don't know many gay women so I haven't had much opportunity.

I recently spend a few days with friends, and one of the women was the sister of a good friend. I think she is amazing and I'm very attracted to her. But I don't know if she is bi/gay and I feel the situation is a bit delicate.

I'm looking for any advice on approaching her subtly so that I don't offend her. And if she is and the feeling is mutual, I'm also worrying about how this might affect my friendship with her sister. We're all adults but if she is bi or gay she's not out to her family.

This all feels very complicated because it's not often I'm attracted to someone to this extent. I can't stop thinking about her!

What to do?!

 

Thanks Bree!

That's good advice. Only, I live in a very liberal place, so it's unlikely anyone I know would be anti-LGBTQ issues, at least superficially. I think the even harder thing for me is the fact that she's my friend's sister! That makes it even more delicate...