This is great information. Though at 18 weeks I wouldn't expect he'd get too much bigger? My old dog was 2 pounds at 6 weeks, and she grew to be 14 pounds. What did your pup weigh at 6 weeks?
Funny, i have just had to order a second set of fleece sweaters, one size up. 3 weeks ago I had to cut up a sock as a sweater because he was too small for the first XS sweaters I bought.
Mine is now 3.6 pounds at 12 weeks, all the charts say he will be between 7-8 pounds. He is a mix, but a mix of toy breeds. Boy did he sprout legs all of the sudden!
I really want to get a good, heavy coat for him, but I imagine I do still need to wait another month at least. For now I am doubling up on sweaters. He doesn't seem to mind still looking like he is an orphan in the meantime