He doesn't look like a dwarf to me, but I'm no expert. If he's only 7-8 months old then he's likely not done growing yet. I have one chin that is a healthy 530 grams. When I hold him I can't feel his bones and he has a nice squishy tummy. I also have a rescue that came to me anorexic, he was 450 grams when I weighed him last. He is extremely bony and noticeably small for his frame. I had him up over 500 grams for a short time by giving him a supplement, but as soon as the supplement stopped, he dropped the weight. He's got a list of issues, but my main point with him is that he looks skinny and feels skinny. Your boy doesn't look skinny to me, just not full grown yet. Give him some time before you start stuffing his face with junk. You wouldn't feed a kid a bunch of candy to make them grow big and strong. I don't think the rescue lady is right about Rory at all, although it does sound like she got the great chin parents part right.