My daughter is gothic? Please help. Pictures included.?

[Anna]

My 16 year old daughter is gothic, she's been like this since the 8th grade now and I don't know what to do.
We come from a Christian family and I know she's an atheist, I've tried to welcome religion back into her life but she refuses.
All she does is go in her room with her damn black cat Casper and read, she's currently reading Dracula. She also has a TV in her room in which she watches Netflix, all she does is watch horror movies and watches documentaries; she recently watched a documentary about the origins of Halloween and one on a haunted asylum. She watches the show Ghost Hunters a lot.
She writes a lot as well. She's a nice kid, she's not shy at all but prefers to keep to herself and people she likes. Isn't rude to me unless I start asking why she dresses like a freak.
She always has her earphones in, she listens to stuff like The Cure, and Marilyn Manson.
Her black cat literally follows her around, she loves him so much and I think she talks to him, is this the devil possibly? She has a ouija board in her room I think she uses to contact the dead.
She has a tattoo of an inverted cross and underneath it says "Believe in Yourself" I DID NOT LET HER GET THIS, her friend did it for her.
This is her - http://tinypic.com/r/35bc7jr/6 (she's a natural blonde can you believe it!)
Her boyfriend - http://tinypic.com/r/fz9s0l/6
Her boyfriend listens to a lot of really heavy metal and is a very nice, respectful young man I just hate him because of his piercings (he has his nose pierced now too!). My daughter was goth before him though, they've only been dating a year.
They both have decentish grades.
PLEASE ANYONE HELP I'M DESPERATE, I wish she was a nice cheerleader and was into regular girly stuff like the other girls her age.