When I was feeling much as you do a year or so back, I emailed Leah Day in despair, and she was kind enough to reply. Her advice then - and I've heard her say the same thing again since - is just get a quilt on your machine (or a practice piece) and quilt it. Don't undo your work don't fret about the imperfections. When you look at the whole quilt, they're often impossible to find anyway. I think she's right - now I look at a quilt that, at the time, I thought was a disaster, and it really doesn't look that bad. And if you can just relax into the quilting without stressing too much, you're probably going to find your rhythm more easily than if you're tense. I've done much better with FMQ since I decided to stop worrying so much about the results. I start by confirming that the tension is basically OK, do some warming up on a practice piece, and off I go! Admittedly, I haven't tackled a really precious quilt, but I'm moving towards the point when I'll be ready to do so.
Would really recommend Leah's Quilt Along, which someone else has already mentioned. She explains things very clearly and is so encouraging.