How visible your mistakes are to others, partially depends on how much contrast there is between the thread and the fabric colors. You don't have to use the same color top and bobbin thread. If you choose a color that blends in with a small print or tone-on-tone backing, errors won't show up there.
And, of course, once the quilt is washed, the errors won't be as visible. You're doing well, so be brave and quilt on!