did the batting not come with care instructions??? if it is packaged it probably tells you-
the wool batts i have used do not shrink- and wash up beautifully in a quilt- they are my favorite batts to use- i would think one with alpaca/wool blend would be very nice too-
they needle beautifully- are lightweight, lofty and mine i toss into the washer & the dryer- they come out just snuggly soft, fluffy- wonderful- i have wool batt quilts that are used alot & laundered a few times a year- have held up for a number of years with no issues- will be passed on-
you need to quilt it to the recommendations of quilting density (some batts can have up to 10" between quilting lines- others need to be quilted every 2"- it's important to know and quilt as much as is needed) my wool batts have allowed 4" between quilting lines.
if you do not know any of the details for the batt you purchased - do you have a business card/info from whom you purchased it-so you could contact them & ask- recommended quilting density, shrinkage rate (warm & natural has a 2%-4%) laundering instructions...and any other questions you can think of- if it is packaged all of this information should be on the package.
your quilt is beautiful- i love using wool batts and will have to watch for one of these- if i could afford it all of my quilts would have at least the wool- it is so wonderful to work with- and makes very luxurious quilts.