I found myself using the non-thimble finger, too, so I put a thimble on every finger. Yeah, THAT really worked. Not.
Now I quilt without a thimble on either hand and use my index finger nail to push the needle. No, I have never gotten a hole in the nail. No, I have never run the needle up under the nail bed. Yes, I build a small callus on the underneath finger. I rarely quilt more than an hour or two at a time due to nerve damage in my hands, maybe that's why I can manage this.
Jan in VA