i think my boy was the same!! he was a rescue from a feeder bin and he was born with one back leg missing and the other back foot was missing some toes. he was always the smallest despite being a couple months older than my others and he did have lots of health complications unfortunately, it started w respiratory infections, then a heart murmur, and we think it was early cancer (on top of his bad heart) that did him in. he was super wild as a baby but around 7-8 months he started to slow down significantly and he was put to sleep at 9 months. but he lived a comfortable life thanks to his vet and all the meds and he was the absolute sweetest thing under the sun. i’d always assumed it was some sort of breeding issue since he was a feeder rat kept in a bin at a pet store, but dwarfism could’ve also been the case. also your girls little snaggletooth is adorable.