Not sure if you are using a walking foot, but that will help move the quilt sandwich through much easier. I've found that I do need to increase my stitch length slightly for the quilting process...if I don't, then the stitching lines look tight and strained. As someone has already suggested, it is best to experiment on a practice sandwich so that you can determine which stitch length will give you the look you are going for. As you stitch each sample line, use a Sharpie marker or a pen to label what the stitch length is so that you can use it as a reference later on. Congrats on making your first quilt and welcome to the board!