There is no right way. If you like the way it looks, then it's right
I usually prefer symmetrical, and might feel obliged to add a row - but that's just me (more likely I would have resized the blocks to make it fit with a symmetrical layout). I try to fight that need, because asymmetrical often looks awesome.
Keep in mind however - if it fits perfect now, it will likely shrink when you quilt it. And again with you wash it. My "fits perfect" quilt for my bed is now a couple inches short all around. The border that was supposed to start the drape now frames the bed instead. So you may wish you had added that row later, if you really want it to fit right on top.