Aw he is exactly one month shy of Ryan. Ryan will be 6 months on the 7th.
Yes, it is large, but there is nothing wrong with that as long as he is healthy for the time being. Ryan has not been weighed for a good 6 weeks but he was 17 lbs 6 weeks ago.
When he starts crawling, the weight will fall of if you think he is chunky. I would not worry about that kind of stuff personally... actually I think chunky babes are cute.
Mine will be 5 months on the 4th and at his last appt 2 weeks ago he was 17lbs8oz and 26 inches so no your baby doesnt sound big at all he sounds healthy.