Could my sister be bisexual , are these signs of her being interested in girls?

I know none of you will be able to tell what her sexuality is 100% just by a few details about her but i just want your opinions. I'm Catholic and homophobic just to get that out of the way and no i'm not a bad person i just dislike gay people - a man was made for a woman. I know people tend to be more accepting now that it's 2016 so if you gotta problem with my homophobia then leave. Ok so let me give you a few reasons as to why i think she may be a bisexual. Now, i don't believe she is fully attracted to girls because she has always been interested in men but still, the though of her even being slightly into women grosses me out.
- she's 15 years old so- it may just be a phase because i just started noticing these weird things
-she has a tumblr account and i stalked it once - all she reblogs is pictures of naked women - VS models and she follows this one page called "petite girls with big tits" she reblogged once a quote about loving a girl and many of her quotes have the pronouns "she, her" she hardly reblogs any naked men etc.
- i asked her a few weeks ago if she was interested in girls and she got really mad and denied it plenty of times
- she keeps talking about this "cute" (in her mind) lesbian couple. She's obsessed with them
- we were talking in her room late at night. We were talking about relationships (she's never had a boyfriend ) and she said she "wanted" to "turn" lesbian because men were rude, shallow and terrible. But i think she's actually just interested in girls and wants an excuse.
- i caught her masturbating to lesbian porn
- she has thousands of pictures of attractive girls in her camera roll
- she always talks about her celebrity " woman crush"
so, what do you think?
Could my sister be bisexual , are these signs of her being interested in girls?
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