I haven't looked at the pictures, by don't worry so much about weight and focus on body structure. There are far too many variables at play to say what a yearling "should" weigh. Also keep in mind, many people over feed trying to grow their snakes faster and many are overweight.
I trust dakski 100% so if he says your boy looks good I can confidently say trust him. He's extremely knowledgeable and I'm familiar with his crew, they're all in fantastic shape.
P.S. Dakski....I'm on IG, hit me up!! snakes_and_grins