I ran the calculations, and I use the same priming rate as you. I also usually do at least 4 weeks in secondary, but I get good carbonation in less than 6 weeks.
I dissolve the sugar in a small amount of water, and boil for 10 minutes, cool, add to bottling bucket. Then I rack the secondary into bucket and stir gently to mix.
After bottling, I keep the beer at about 70 F for three weeks before moving to the cellar (which is a bit cooler).
Edit: Being English, my preferred carbonation rate may be considerably lower than yours.