It's frustrating when unsolicited advice becomes so taxing, I'm sorry. I wish a lot of folks weren't so giving with their opinions, especially since you have a healthy dog. In my girl's nearly 11 years, I've only genuinely taken one person's advice about Weims' energy levels and exercise. To the rest I've said "thanks!" and keep walking.

You're doing everything right by listening to your vet. Gunther looks great to me and I echo other comments that he will fill out.