Sandie and I are working on the exact same thing right now - she likes to counterbend as well and it's ruining our circles! Here's what my trainer always tells me when I'm trying to get her to bend:
* Outside leg slightly back
* Inside leg pressing (hard) into the inside
* Outside rein is steady, but inside rein is slightly shorter, to "pull" head to the inside -- keep in mind though, your inside leg has to be very strong, or the horse will just make a sharp turn inward
* Outside shoulder pointing forward (very slightly!) - this really just helps you pull the inside rein in a tiny bit
Eventually you won't need to have the inner rein much shorter, it may need to be more pronounced at first, just to teach him to bend in - but it needs to come mainly from the legs. My trainer always reminds me too "whatever you take with one rein you need to give with the other" because if you're yanking on both at the same time you'll just confuse the horse! You look like a pretty good rider though, I'm sure you and Dakota will get this very quickly!!
Good luck, hope that helped you out!!