Unless I'm not reading your description correctly, I don't see where you're doing anything wrong or illegal either.
If you're in the far right side of a left turn lane, parallel but not in front of the turning vehicles, and proceed to make a wide turn remaining to the right of the turning vehicles, you're safe and out of everyone's way.
Technically, you have the legal right to take the turn lane in front of another turning vehicle, but that just pisses off the drivers and creates another unknown.