"is it normal that i wanna f*ck my cousin?"

When I was 15 and I started to have this major attraction towards my cousin who was 15 too. Me and her aren't really that close when we're together or alone we don't really talk all we do is have these akward conversations as if we didn't know each other. Well besides our relationship when we were about 15 I started to notice she was getting real curvy from everywhere And after I had noticed all that I started to get this extreme urge to f*ck her you know, and well time passed and then this one time when we were out on a jog I was talking to her about how she feels about incest, she kinda got embarrassed about it cause I asked her if she ever would f*ck with a cousin and she didn't really answear the only thing she said was "um....well you know your my cousin and I don't see you that way cause it's wrong". After that we kinda separated a little from each other like we didn't talk to each other that much or see each other, over time we got over that and things were back to normal. Right now the both of us are 18 and I know she still remembers those things that I told her we never brought that subject up again because I noticed every time we talked about any kind of sex or anything else she gets nervous, and gets uncomfortable. And whenever I compliment her that she looks beautiful one day or that her butt looks bigger in jeans she looks at me kinda nervous or a little bit of why I'm checking her out, it's not I try to get her mad it's that I can't stop checking out her amazing body. And many times when shes at my house shes falls asleep on my couch, and what I have in mind is to try to seduce her in her sleep but I do what I can do to try to fight temptation by not doing anything at all. And a few weeks ago 2 of my guy cousins were at her house and they invited me over to just hang out, and so we all hung out for like a hour or so then my cousins had to go somewhere cause it was an emergency or so they left me and her alone, we started watching TV for like 30 mins and suddenly she falls asleep on the couch and I find myself talking to my heavy sleeping cousin laying on the couch so sensually and it didn't come to mind to seduce her until I thought about it that it was the perfect timing to make a move on her like I always wanted to, and suddenly I got rock hard down there and decided to take it out and maybe wake her by slapping my you know what on her cheek and waking her up or to put it in her mouth cause her mouth was open perfectly but as soon as I come to approach her many things went through my mind like what if she wakes up and panics. Many outcomes went through my mind so I didn't do anything at all I just backed off and put my penis away as I sat there thinking looking at her and she just kept sleeping in those same sensually positions. I honestly was scared to see in what way she would have reacted, I found out I had the courage to take my penis out but not react in such a perfect situation like this one, I kinda had it planed out in my mind because I had a condom, we were alone. What I'm trying to say is that me and her normally have this sort of tension between us, sort of sexual tension you may say. And I'm not like other guys who just wants to hit it and quit it, it's that every time I see her I want to make love to her, it's that I haven't got the chance to tell her anything that I want to be her first because who is she gonna trust to give her virginity to some guy like a boyfriend that just wants to do have sex with her and end up breaking her heart in the end or me her cousin that shes known her whole life and can trust to be wih her whenever she needs comfort and won't just have sex with her only once to get rid of temptation, no because I want to be with whenever she need satisfaction from a man, comfort, and just someone to be there with her. So my questions are how do I tell her that I feel this way about her? How do I start? What do I say?
And what if she feels that same way and understands?