If you come from a place, you grew up there or where born there.
The main character in Living English, Anne Lee, comes from Singapore.
Example: She comes from Singapore.
To fit in with a group of people is to feel you belong because you share similar beliefs.
Example: He hates sport, so he doesn't fit in with the boys who like to play football.
To miss out is not to be involved in something you would have enjoyed.
Example: I missed out on that job I wanted.