Hi! I dont know if you will check back and see this but my mini is skinny too 🙂 Shes 8lbs ALWAYS. Never fluctuates. I have been told this is not only the norm but a very good thing since they are predisposed to disc issues with obesity. Your pup looks just like my baby except mine has thicker red hair (she is a micro-wire haired) so that could be why the skinniness is more exaggerated with your pup. Hope that helps assuage your fears!