It's a very elegant item - lovely. I can't answer your question regarding the when, the where and the who (might have made it) but I'll offer you my opinion on whether it could be considered to be Carnival Glass.
I like to define Carnival as (press) moulded, iridised glass with a pattern. Some Carnival items were also blow moulded, but mainly they were pressed. Like all definitions it's open to discussion and disagreement. Some collectors don't include the notion of pattern - here's a definition off the CGCAA website "Carnival glass is press moulded iridised glass made mostly in the early part of the 20th century". My own feeling is that a pattern of some sort (usually moulded) should usually also be present.
If I use my own definition then your piece fits the description. It's moulded, it's iridised and it has a pattern. It isn't Classic Carnival Glass of course (that applies only to USA made from the early 1900s). I can imagine that a "purist" would say that it's not Carnival, but if one abides by a reasoned definition and qualifies the item in the description, then, imho, the item is a form of Carnival (even though it might be at the edge of what most people "see" Carnival as).
I imagine a debate on this amongst Carnival collectors would throw up a diversity of opposing opinions.
Glen