Is it a negative that my PhD research has been in several unrelated areas?
To the degree that you do have a PhD thesis and some other work (that, more over, has been published), I would say it is a positive thing, not a negative one. It is a good combination of "breadth and depth" as one comment has put it. The general advice I have heard many times for long-term planning, is "the ideal is to try to distinguish yourself in two fields inside a discipline. One -everybody tries that. Three -and your image starts getting blurry". Or something like that (and with the caveat that "fields inside a discipline" may not mean the same thing for different disciplines).