With very little time, I'm normally the one who goes for all the short cuts in order to get anything done, but I'm still starting and finishing every row of quilting with fairly long pieces of thread. I then thread the top one through to the back, make a simple knot and bury both threads in the wadding. You can't see them, there are no bumps and it lasts forever. I often do this sort of thing whilst watching something mildly interesting on tv.
No idea what you are doing wrong so that the stitch length varies. Have you got a quilter living in your area who could watch you and work out with you what's going on? One time my stitches got very small until I noticed that I had put my foot on the quilt so it couldn't move through the machine (that's life!).
I actually keep (and use) those of my early quilts that would easily make it into any 'Top 10 Worst Quilts' competition. They are very comfy, and warm, and much loved. I'd never let a seam ripper get anywhere near them. Those babies have character - lots of character. I'm not perfect, so I don't expect my quilts to be. That doesn't mean that I don't try and produce pretty decent pieces these days where everything meets where it should, and that hang flat when exhibited.
Lorchen