Basically this is how I do my QAYG too. You just have to find what works for you.
a couple of years ago we were at our cabin & I had just seen a method like this here on the boars.
I layered my quilt sandwich on a queen bed, the quilt top was in rows. The batting was fusible.
I had the ironing board in there & a sewing machine. I pressed down the center row with steam to fuse.
then I took 1 side, put it face down on the center row with seams alined.
Lifted the sewing machine on the ironing board & sewed the seam. Put the machine on the floor, pressed the seam, then did the next row.
after the side rows were on , I attached the long side borders. Next came top & bottom borders with corner stones. Forgot to mention that the side rows already had the sashing attached to 1 side & the center had sashing on both sides.
Anyway, easiest quilt I ever assembled. But then I had to quilt it. So the next time I changed the method & did it at our main home & with each row did the quilting before adding the next row. So now that's how I do it.
good luck, and just keep trying