I can't sew without one

Me too. I use Clover brand.

I can't use a thimble due to long fingernails.

I can't use a regular thimble, but get on well with an open topped one (tailor's thimble). Using one of these, you push the needle with the side of your finger, rather than the end of it, and it's much more comfortable for me. I have big fingers, and sometimes the thimbles don't stay on all that well, so I put a small quantity of Blu tack inside, which is slightly tacky and that keeps the thimble in place.

I'm a lefty so I use a leather thimble on my left middle finger and a finger cot on my left thumb.

I use the ones with the little lip on them, and a hole for the long fingernails to fit into.

Mom used the hard metal kind but I have a "bump" on my finger and can't use that kind. I found some self-adhesive leather dots that can be used over and over and I love them. I've also used the clear plastic dots and they work well too.

I found rubber thimble thingies at Hobby Lobby... I think they are mainly used for handling fabrics....I love them...they are differently sized for each finger
They are red and come in five (5) per package...can ya tell I'm a newbie..tee hee

I recently saw thimble that might help you with your bump. They have a soft, silicone sort of part that fits over your finger, with just a metal top to them. I think Clotilde do them. (Protect & grip: http://www.clotilde.com/list.html?cat_id=143 )

I have a thimble from Clover that I love. It is leather with a small metal disc. I think it is called a coin thimble. I can't hand quilt without it!