When making your own fabric sheets, it is best to use the Bubble Jet Set and Bubble Jet Rinse to treat the fabric first before ironing it to the freezer paper. Most printers, even those that use Durabrite inks, will wash out most of the print if not treated with Bubble Jet Set.
Check out www.cjenkinscompany.com for lots of good information about printing on fabric.
The sheets that you bought at Michael's, which sound to us like iron-on transfer sheets....will eventually crack with washing and your pictures will be lost or ruined.
Printing directly on the treated fabric makes the pictures last longer and be more vibrant. However, with time, they will fade. Keep the finished quilt away from sunlight and do not wash very often. Good luck!