Are you using a walking foot? Did you stretch your backing & top taunt when you sandwiched it all together? Do you use basting pins to hold it all together? Even when I use basting spray I still use some basting pins to keep it all together. When I have a quilt that is too large to sandwich together on my table top I have to do it on the floor. I will tape the backing to the floor (pulling it taunt) and then tape down all the sides with sealing tape. Then I layer my batting and then cover with the top (again stretching it taunt & taping the top to the floor. After that is done I will pin baste. If I'm doing all this on my sewing table I use industrial clamps to clamp the back & top to the table instead of having to use tape. Hope this helps. Please don't give up. Try a different method.