Maybe you are moving the fabric too fast? I just had a class on fmq and started everyone the way I was taught. Use no thread and "trash" paper. Just get the feel for the moving and aim to keep your stitches the same distance apart. Just keep at it until you are pleased. Then and only then go to fabric "sandwich" add thread and see how much more control you will have. Also, a bit expensive but invest in a "Supreme Slider" it is teflon and your fabric will glide over it. Just google Supreme Slider to see what it is. I use the slider and quilted a queen on my Janome mc6600. super nice
Barbara