and "not always there"

hi everyone.
i really intended to not post anything today. i don't know. i just want to be one of those rare, awesome people who are not always there. like, you know in films and such when someone's looking for somebody and then that somebody isn't there and things go wrong just because? yeah. that's cool. it also occurs, when you wanted to contact a person online. say, an online shop or something and then when you call, they aren't present? and your mind goes like: "oh well, that guy's probably busy. doing some other awesome shit."

well i never wanted to be busy.
anyway,
how do you differ someone and somebody?
i use someone when there is a particular, specific person i am pointing at. say, someone broke my heart. or, someone stole my favourite mug.
and then i use somebody when the person involved is unknown. or unimportant. say, somebody got you pregnant. or better yet, now you're just somebody that i used to know. see? unimportant.
i am not sure about that, though. grammar rules so often stress me out.  it does not really matter.
nothing does.