Read other letters about this article
I rejoice with you that things are going so well with the kids. AND that you and R have found each other. Hooray on all those fronts! And fingers crossed for the school selection.
When I read your plans to move so fast, I felt DREAD. (1) I know how hard it is to "uproot" kids. Unless they're bred for it (parents in military etc.) it's an adjustment. High school is such an important time. (2) I know how VERY different 'dating' and 'living together' are, especially once one has lived a bit and has preferences and habits.
Seven months isn't that long - you're still in the glowy phase.
My story: I lived in an allegedly more desirable area but I moved so my (female) partner's daughter could stay put through high school. It's only six more years. My only regret is that I burned too many bridges in the move, reducing our options for later. My advice would be for R to rent his house for 1 year and move in with you and see how that felt for both of you. Not ideal, not romantic, but get through the time when the glow wears off before you decide to uproot the kids. Right now I worry he's having things too much his way.
As a sister feminist I support your right to have the wedding YOU want. Once you've sorted out the rest of this, it'll have been worth waiting for. And the kids will WANT to be in it. Best of luck!