I'm not sure I can be helpful.
I discovered two things about my own nails (or lack thereof): 1) I can't stand having long nails, even when they do grow. If I can avoid chomping on them, I still need to keep them short. 2) I chewed on my nails out of anxiety, even in my childhood. Not real worry - just a general personal nervousness that kept wanting an outlet. Interestingly enough, when I ended up in a *really serious* situation - a granddaughter was born with a heart problem, and had a valve transplant when she was less than six weeks old - I stopped biting them. At least, by and large. I still nibble a bit, but that's often related to their growing (see #1).
I wouldn't want to wish such a situation on you, but maybe it will help you think about why you chew on them in the first place. Let us know if the band-aid thing works. Another possibility, if you have the funds, is to have your own nails professionally manicured twice a week for several months. They will look so nice all the time, and you'll know how much you're spending to keep them so, that maybe you'll forget about wanting to snack on them.