"is it normal that i've fallen hard for this man?"

I'm pretty crazy about this guy, I'm 18 he's 23, but that doesn't seem to be much of an issue. We both mutually respect each other, and have similar moral values. I'm mature, and so he is he, so that's not exactly a problem (well in my eyes it isn't). We started talking earlier on the year and our conversations have been progressing. I met him through his younger brother that I used to hang out with 2 years ago, we didn't really "date" because it wasn't serious nor didn't last very long, however, we did kiss, but again...it wasn't intimate. I'm not sure how he would feel if he knew i felt this way about his older brother. I didn't pick to like the older brother, and at first it was funny to me that I fell for the older brother but now I've seriously fallen hard. I can't stop thinking about him, and the chemistry I feel between him is the most I've ever felt with anyone, ever. I don't think that the older brother knows how I feel; but I've initiated a lot of conversation & asked him for his number, etc...You think he would have some sort of idea, right? He's kind of shy, and sometimes funny with me, but not forward at all. I don't know if he's the initiating type, but every time I make some sort of advancement with him whether it's a hug or something more personal in conversation, he's 100% receptive to it. I feel like he's playing it cautious or maybe has no idea how I feel. I just want to take things slow because that's the best thing to do at this point. I don't want to lose him from my life by telling him that I like him, so I keep taking small steps and waiting but it would be nice if he reached out here and there to me. I'm a pretty objective person, I cannot say that he likes me because I don't know what he's thinking; however, I can state that there is something brewing on his end, whether it's attraction or intriguement with me. We stare at each other a lot in conversation and smile. P.S. I've tried to give up on him plenty of times thinking it would never work, but somehow he keeps stumbling back into my life without me looking for him. There's literally no one else in my life that I want to be with. I keep meeting new guys but I don't care about them and my friends think that like something is wrong with me, being I just started my college career and I don't care about mingling. But I'm wondering if i'm crazy for trying to pursue this. I mean you only live once, right? So you guys tell me, Is it normal to grow and fall for this man?