Though it's drastic, maybe change schools? Though not right away, I'd do that mid year. no I'm not crazy
. Combine that with counseling so she can increase her self confidence?
The Help me Be Good book series is really a nice set of books that goes through social situations where kids might be bossy, mean, lie, steal, all sorts of things. Though theyr'e designed for kids up to about age 10 ish, maybe they'd be something to look into about her bossyness.
And I'd never move Karma (my daughter) at the beginning of a school year, I'd do it in the middle.
Here's why, in the middle of the school year (say at the semester) she's the only new kid. Everyone wants to know who she is. Groups of girls usually "fight" over the new girl. At the beginning of the year all the new faces blend in and a kid can feel soooo totally alone. (My parents moved me (divorce situation) and I didnt make friends for over a full year) (then moved again in HS and again had a ton of trouble finding where I "belonged" and fell into a bad group).