Are you sewing on each piece, by machine, on the line, dot to dot, right sides together, then Flipping it? It's hard to imagine how you are doing all these y-seams by machine. I would want to sew, flip, tuck the other seam allowance under, then hand sew that other half of the y-seam. This is not what you are doing, so I'm going to wait for your pics of how you machine sew this and/or a video. I think you are on to something new and adventurous (and brave). .....You go girl.....we are all cheering you on.