puffy side,
 

I just made a reversible lap size quilt , it was nice and flat when I turned it inside out , because I wanted to tie it, but then I saw its lose on one side, any ideas oh now to get it to look flat and tight. did I explain it right?

It's kind of hard to picture what you're describing. If it was flat when you stitched it and nothing shifted, then it should lie mostly flat when you turn it....you're sure you caught the batting and it's not bunched up inside???
Whenever i use this method, i always stitch all the way around the perimeter after i turn it right side out - from 1/2 - 1" depending on the quilt. This makes a kind of false binding and keeps the edges from shifting.
Sorry...guess i wasn't much help.

yes,i I did it the pillow case way, but I sewed around the edges, to sew the opening shut and make it look like cording. so if I iron it, there will be a big pleat toward the outside edge!! a mess.

can you try to ease it in? are all the edges of the batting sewn into the seams? that could make it a bit puffy. can you iron the quilt and make everything stay flat. that might help.

I would take your edge stitching out first, then smooth it flat & iron it.... then pin it and do your edge stitching so it doesn't shift and then the tying.

Did you use your walking foot when you sewed around the outer edge? Is your backing fabric cotton fabric or something else like flannel? Just trying to get a sense for what else might have happened.

A few years ago I made quillows and found if I cut the backing a mere 1/2" smaller than the front all the around, when I turned it, the front side curled over just a hair, and that back was never seen from the front, and it did not pucker as I secured that sandwich........I do that with all small stuff too........works for me....might help you

Anytime you turn something inside out you should give it a few shakes til it starts to smooth out. I also leave the openings to turn inside out large enough I can get my hands in to straighten or smooth out. Then I quilt it.