Is he uninterested?! I sometimes send him messages, but sometimes he wont message me back….why?

ive been crushing for months now on this boy I don’t even know, I saw him at his work and ever since, I cant stop thinking about him. I sometimes go back, but I haven’t gathered the courage to say anything more than a “hi”…anyway I managed to find him online, so I messaged him. sometimes he wont message me back….why? I don’t know much about him, but it appears to me that he has a low self esteem, im not sure about this but I do know that hes shy…and I don’t think hes ever had a girlfriend. anyway, I think he got the wrong idea of me- by messaging him, I was really straightforward and I tried to sound confident without being too presumptuous, im generally really coy myself and ive never had a boyfriend but I think I came off maybe too experienced, desperate or intimidating…(as I got help from my friends on what to message him…& they are generally better and more experienced at talking to guys than I am.) in one message, I casually asked him for his number (something I wld never do) …but he never replied. he only replies sometimes. is he just being nice? I don’t want to be one of those creepy messagers! my friends are like “don’t waste your time”…but I cant help it, I feel a connection w/ this boy. strange I know. and I don’t want to sound big headed or anything but a lot of people think im pretty. but does he? or am I just creeping him out? what should I do? if he doesn’t respond to some of my messages what does that mean? does it clearly mean hes uninterested? someone suggested to me that maybe he doesn’t want to sound lame, which I could believe, because in some of his responses- im not gonna lie, he sounded pretty lame! but I don’t care, I think its cute. I honestly think hes uninterested, but im in denial….but then another part of me feels like hes too self-doubting to think I would really like him. but hey, am I being oblivious?! afterall, he has ignored my messages several times… I don’t know! I would appreciate any feedback!