Starting to doubt myself

I am a male, roughly 20 years old (IDK if you can see my age on here, but if you can;t, I do not want to give out my age). I am not Gay or Bi. I am slightly transsexual, but I mostly feel like a man.

Now if you are ready to give advice, I need you to read EVERYTHING in this. I am going to explain myself thoroughly so that you have a very good idea of who I am.

I am a Christian, born and raised, and reborn if you know what I mean. I have had an insane sex drive for as long as I can remember (actually before then, I was under 10), even before I knew what sex was (or that it existed), though I am still a virgin (in fact I haven't even kissed yet). If we were to play the blame-the-genes game, which have been disproven, I would say that my high libido is because of my biological father, who would have sex with my mom several times a day and STILL need to masturbate.

I have been with the girl I am with now (we'll call her Lucy) for a little under a year now, and I hold onto her with a fiery passion. She is in the 13-16 range (again, won't disclose what specific age). We met on DeviantART, and to give you an idea of how far apart we are, If I were to live in San Fransisco CA, she would live a little farther than Austin TX. I won't say where in the world we are, but let's just say that I would need a passport to get to where she is. and I have never left my country, and I have only been to like 2 cities that are right by each other, meaning I have never met her.

Now I have tried VERY hard to convince myself that I don't just want her because of sex, however, I am starting to doubt my motives. Lucy has mixed feelings about sexual things, however I have, in the past, hurt her with sexual things unintentionally.

I have doubted about my motives, but I have major counters to my doubts, which are the following:

1) I left another girl (Jade) for Lucy.

This may seem insignificant, and even something that would make me a bad person, but when you see #2, it will make more sense. However, also keep in mind that Jade was WAY more sexual than Lucy. Like drag-you-by-the-heels-to-the-bed sexual. Lucy is super shy and secluded and curls up in shame for even thinking about THINKING about sex, so to me, it doesn't make sense that if sex was all I wanted, that I would choose Lucy over Jade.

2) I have had the choice to be with another girl several times and chose Lucy.

Truth be told, I am a VERY physically attractive male. I mean if Johnny Depp were standing next to me, he would obviously outdo me, but I, for a skinny tall young adult who doesn't work out, am very attractive, and I have had the opportunity to be with other girls. Now whenever I was attracted to/seeing someone else, I would ALWAYS tell Lucy, because I felt that she deserved to know. But when it came time to make a choice, Lucy ALWAYS came out on top, without much of a contest. I even had a choice-point where I had like 5 girls like me and Lucy STILL trumped them all.

Now again, this is a 2 parter. On one hand, she was ALWAYS my choice. On the other hand, It seems that I am not loyal.

3) I have recently quit porn and sexual stories and focused all my sexual attention on her.

She was getting hurt that I would watch porn and read stories, so I stopped for her, but on the same token, my sexuality can be a bit much, especially for a girl that young.

So on one hand I am hurting her because I am too sexual, but when I try to deprive her of that with porn and sexual stories she is also hurt.

4) She has tried to leave me, but I would chase her.

In fact I have even broken up with HER (without another girl involved) and STILL came back. There is a love I feel between us that would just teat me apart if I lost.

So my questions are this:

Do I actually just want her for the sex?

If so, why her and not Jade? Also where do I go from there if I am?

If not, what can I do to take off the sexual pressure on her WITHOUT hurting her? (Note that I do masturbate to her, but that still counts as a sexual pressure on her)