I've often been mistaken for British while at home in the States.

I don't know why. I have an American accent. In fact I made it a point to keep my American accent while in the UK because I didn't want to seem presumptuous by speaking with a contemporary RP accent. But the truth is, such an accent would have come more naturally to me after a year and a half in London than keeping my native accent. In fact, I'd been mistaken for British or Australian in the States at least since I was in my teens and after being immersed in that middle class London accent for so long, keeping an American accent was actually tortuously difficult.

Basically, I have an American accent but it's not very convincing, despite the fact that I was born in the Midwest! It makes my manner of speech awkward because on the one hand, I have extremely British speech patterns like the way I pitch my sentences, or the way I'll unintentionally slip in little Anglicisms but on the other hand, I'm speaking it with a weird mix of South Carolina, Arkansas, London, and West Coast accents. I pick up little regional idiosyncrasies wherever I go in the States but it's more a matter of trying to assimilate.

Also, I tend to be more verbose, using longer words and more precise pronunciation on certain things. This sounds pretty awful with an American accent; I sound painful, shrill, and awkward like an idiot who uses big words to sound more intelligent. But if I speak with an RP accent my vocabulary might not seem as stilted or pretentious because people (especially in the US) expect someone with an RP accent to have a bit more sophistication.

Really, the only reasons I wouldn't would be because maybe I might seem to be putting on airs, like Madonna was (though Madonna's RP accent is frankly forced and painful whereas mine, with practice, sounds pretty authentic). I'm afraid it might be politicized if we go through another era of extreme jingoism like we did in 2001-2003, though in truth there's nothing political behind my motives. I'm also afraid it might get an eyeroll from my friends in the UK, or seem like I'm trying to pretend I'm something I'm not and come off as inauthentic.

Honest feedback will be appreciated.