Also, it can pay to practice falling. My wife got so scared for a while that I took her out to a soft grassy field and we fell sideways for practice. That helped dispel most of the fear.

I don't mean to say that skipping foot retention is some sort of failure. It's not, at all. My saying I much prefer to have it than to go without it is merely a statement of my own preference. If you've given it a good try and don't like it, that's just fine. I am just trying to show you what it takes to be comfortable with it.

Another thing that can help is doing balance practices, which you should do without foot retention. Ride as slowly as you can. Once you're good at this, pick some rough terrain and ride slowly. Even if you don't improve your balance, you can learn your limits of balance, which is even more important.

Another balance skill is to ride while looking backwards and try not to veer off your course. This is an important skill for riding in traffic. A head turn serves at least two purposes: it lets you see what/who is behind you, and it signals to those behind you that you know they are there.