Is it normal to want to have a sexual relationship with my sister?

For the past year or so, I've thought about my sister in a sexual way. I don't know how she feels, and I don't know if I want to tell her or not, but here's my story.

When my sister and I were younger, we would show each other's bodies and development not knowing it was wrong. She would show me if her boobs were getting bigger, or if her pubes were coming in. It would even get as far as us having a friend over and seeing who's privates looked better (keep in mind were only about 7). I could remember being on top of her, rubbing my crotch on hers fully clothed, but she wouldn't think of me, she would think of a neighbor we had. All of these things stopped around the age that she was about to hit puberty, so I would say around 11 or twelve for her, but maybe even earlier.

While growing up in never thought of these moments, nor did I realize that it was wrong. I never looked at my sister and thought of how sexy she looked. But now I'm 18 and she's 19 and she's all I think about. It was around middle school that I started puberty and by that time I had constantly thought about her. She normally wears revealing clothes, and it's hard to keep my eyes off of her. I don't know if she does it on purpose but she's definitely not a whore. I really want to tell her and at least try it onceto get her off of my mind, because whenever she's around I can't help but imagine. I wish I knew if those feelings I developed because of those early activities had an effect on her. But for now she's all that's on my mind.

I need some guidance. Is it wrong? Is it normal? Should I go for it? Whether you're against or for the situation I'm looking forward to your feedback. Thanks!