He's a beautiful boy!

There are much better indicators of potential adult size than just the weight.

Have you measured his height, taken a good look at his bone structure and size of his feet according to the rest of his body?

In the photos, his bone structure and size of his feet indicate that he isn't going to be a huge or oversized Golden. If he's 21 inches at the shoulder by 6 months, he should easily reach the ideal breed standard of 23-24 inches by the time he's a year old.

Not all dogs grow in the same stages and he still has a lot of growing to do.