Congratulations on your puppy..Most of the vets offices(unless they use a baby scale), use the big scales that weigh by 10ths instead of 16ths, so maybe that is why you're getting different weights. 2.8 at the vets office would be 2 1/2 lbs. and he's not quite that, so most likely, he will be between 4 1/2 and 5 lbs full grown, although, that's just an estimate..
I use
www.photobucket.com to upload my pictures, then you can just put the link on here..I never could get pictures to load on this site, it says they're always too big..