That seems like an excessive amount of shrinking from quilting.  I quilt everything to death and only lose 2-3 inches. 
Do you prewash? What type of batting are you using?

Even if it was an all cotton batting and no prewashing, 10 inches seems like a lot. 

I pre and post wash. But it's pieced at 90x100, and when put on the bed it's 80x90. Wasn't a dis on the quilting, as it looks pretty...just trying to figure out what size I should piece it to make it end up "right" in the end :D 

Definitely prewash, as hot as possible. Batting, Cotton Dream Request. Post wash after batting, dry to damp, stretch out to finish.  Still...wasn't trying to dis the quilting. What size do you make the quilt to be an appropriate size *after* quilting on a queen bed?

Why hot?  Mine don’t shrink that much.  I wash quilts in cool with as little agitation as pos…. Mostly line dry or partial dry and then fluff with air or low heat.

hot water and high heat are hard on fibers.

Always have. Get any bleeding done with. What SIZE?

I usually do 80x80 or 80ish x 90 

What I've done in the past is measure the actual mattress including the drop on sides & bottom, the maximum I would want without touching the floor (typically about 6-8" from the floor).  That makes them a little long, but gives some room when someone is in the bed to move around while still staying covered (I am cold natured).  also I don't really like seeing the dust ruffle much.  I have also folded up the corner of the quilt so that it doesn' touch the floor on the corner and tacked it to keep it there with a couple of hand stitches.  You don't see the border that way, but keeps me from tripping/stepping on it as I go around the bed.  If you like to fold the quilt over the pillows (old school style) include that as well.

Really it all depends on what you want.  Since you are making it, you can make it custom exactly how you like it.  If you are making it for a gift, I just use the standard comforter sizes plus some extra to be generous.

I like using a king-sized quilt on my queen bed.  I don't like using a dust ruffle at all.  A king gives me just the right length of "drop" for my queen bed, as I don't like the quilt to hang too close to the floor.  (I have a timed "night light" under the bed, like for short trips to the bathroom.)  But also, the adjustable bed that I bought last year is significantly taller than a "regular" bed, and I have to use a little step-stool to get into the bed without straining.  Yikes!  (I have stayed at hotels where it was difficult to get UP into the beds!)  So, I would need to measure very carefully to allow for height, and add even more inches to a "normal" king-sized quilt, if I wanted it to fall closer to the floor.