So fun! Definitely a Pereskia and perhaps P. aculeata? I added a comment to the pic in your fun photo album too. I grow pereskias in regular potting soil mixed about 50% with perlite or pumice. A cactus and succulent mix would probably be good too. Mine like plenty of water when they have leaves, and then not too much when they drop their leaves in winter. One of the few cacti (yup, it's a true cactus) that don't like to air-dry/heal over before being planted when cuttings. You're doing great with yours--I think I'm envious, LOL. Good luck and happy gardening. :)
It's a Pereskia godseffiana; I've had one for years. Give it as much light as possible. Mine is in full sun all day down here in Florida.
Cute plant! I want one!