My heart breaks every time I hear of someone starting quilting on a real quilt they intend to keep.
All of the free motion quilt patterns take time and practice. You need to develop a rhythm, a "muscle memory", and a sense of where you've been and where you need to be on the quilt - and do it all at the same time. Equate it to somone leaning how to drive a manual transmission with no lessons and starting them at the top of a mountain pass.
Put scraps of fabric and batting together and practice on those until you are comfortable. I have tons of little scrap sandwiches laying around with practices of this and that motif. If there is a new motif I want to use, I'll practice it 3-4 times or more if necessary, before I attempt to put it on my quilt.