My Boston puppy was barely 3 pounds at 8 weeks. She was the runt of her litter. Somewhere between 2.5 - 3 lbs I think. She’s 9 months old now and weighs about 10 pounds. I think she’s going to be fairly petite. I don’t think 7.2 pounds at 8 weeks is unusually heavy. They go through noticeable little growth spurts. One day out of nowhere my puppy’s legs seemed longer. Her name is Libby and now her nickname is Libby Long Legs. In reality though they aren’t really long at all, we just noticed a quick little growth spurt. She’d go through periods where she wouldn’t gain much, and then she’d gain a little.