Thanks for the info everyone. Is it safe for me to gauge what his size will be based on the size of the parents? I did lots of research before I got him and I've seen repeatedly that the ideal size is 4-7lbs/fully grown for this breed. His dad is approximately 4.5lbs I think his owner said and the mom a little bigger.
Are males generally smaller then the females, or no

Not that it matters, I love him to pieces and he's healthy, I'm just gathering all the information I can.