[Sexual Desire] Sexualizing male power as a straight guy?

Hi, I'm an 18 year old guy and basically I just need a take on my situation, be it philosophical, psychological or personal. Why is male power (e.g big dicks, big muscles, clearly satisfying the woman) the only thing that truly gets me off pornographically when I am a straight guy? I know what you all may be thinking, 'he's gay' and I thought I might be for a long time but I've experimented with gay relationships, sexual and otherwise and come to the conclusion that I'm just not gay? I've never gotten satisfaction from guys sexually or personally? The thing that gets me off about guys is when they represent sexual power. Every time I watch porn I feel so ashamed because nothing else will get me off.. I feel emasculated when I think about sex and I've developed insecurities which have damaged relationships before... Is it some sort of neurosis I've developed through social anxiety? I've always been a weak guy and I was bullied in school for my body. I never played sports as I felt cast out by my male classmates. I'm a good looking guy and honestly have no problem with partners but I feel as if I'm still the same weak child who no one will desire.. Am I sexualizing what I most fear in my day to day life? The Alphas? P.s this is not to say sex and my sexuality dominates my entire personality and that every waking moment is concerned with it, it is just something I've found real trouble with for a long time and I need to understand what's going on for me!!