Is it normal to be this desperate?

I'm a lonely girl, very shy, but I open up quickly once I am comfortable. The thing is I know by looking at someone and talking to them the first time if I'll be comfortable by there actions and words.. Some people I am just too shy around but some I can just talk!
I've never had many close friends and I really want some I'd love to be close to a guy a best friend sort of brotherly friendship. I can tell if people are like me or look lost or so I think? Maybe I can't ? Because dont judge a book by its cover thing.. I saw this guy at a pool, he was alone and not doing much I was going to go over and say hi, he looked lonely but then all his family came in so I didn't want too.
Then I get this feeling of, what if I miss that chance?! So I'll go back the next day and wait around.. It's not normal I know but I get this fantasy in my head of us being so close when I don't even know him?! But he acts so much like me and looks so nice. No one ever notices me :( or comes up and chats :( is this normal? Or am I completely mental?