You can unpick it and the holes will close when you launder it. It takes a LOT OF PRACTICE to do free motion quilting (FMQ). It was brave of you to start on an actual quilt. Most folks practice on small items or practice sandwiches until they are happy with their stitching, then work their way up to a 'real' quilt.
Do a search on FMQ and you will come up with lots of tips.
Good luck!!!