From what I can see, your quilt looks wonderful. Perhaps you tackled a challenging project for a first time quilter. But it sure looks good. Join a quilt club, take some classes, and you will begin to understand how to do things without hurting yourself. And if you are doing FMQ, wow!!
I have done twin quilting and that is about as far as I will go in trying to put something large under the bed of my machine. It does take practice and the more you do, the more your skills build. you may want to do your next project as a table runner or tote bag. Just have fun. Sounds like you love to sew and making doll clothes isn't an easy task. If you can do that, plus make a complicated twin quilt, your well on your way into the quilt world.
Hugs.