My little sister went through puberty a good couple of years later than any of the rest of us (and she had four big sisters with whom to compare notes, so, lots of data!). Being slim also runs in our family, and she was slim (but not anorexic looking). The only difference between her and the rest of us was that she was the shortest; but I've never heard of a connection between late puberty and being short.
Anyway, she did get her boobs and did get her periods, I think she was 16 by the time it all clicked. You might just be in that category. (Unless of course you are so thin that people tell you that you look like you have anorexia. That amount of thinness can affect your periods and your growth.) I'd counsel patience, it should all happen soon enough. If nothing happens in another year, have your doctor run some hormone tests.