I am not sure how much help I can be, but here goes. I drop the feed dogs on my machine, then feed through WITHOUT PULLING. Jeans needles are usually strong enough for this. My other option may not be open to you, I have an old machine which is worked by hand and this is strong enough to go over the several thicknesses/again Jeans needles MUST be used.
I hope you get your quilt finished.
Sandra (from Ayr,in Scotland)