Nice work man, I personally know it takes a lot of effort to gain weight, especially if you have a high metabolism. It took me ages to get to my target weight of 225lbs; soooooo much eating and lifting. I'm really into skateboarding though, and future JJ, so I'm going down to 185lbs. After lots of cardio, I'm currently at 200lbs.
Really though, putting on weight is mad tough. Squats help growth spurts, big time. It apparently releases a natural steroid or Human Growth Hormone, that stimulates your body for growth. When I got really consistent with squats, my overall size and strength jumped substantially. I mean, that's when I really grew. Made me less limber though, but now I stretch quite a bit and do lots of cardio. I'm looking for the perfect power to weight to agility ratio.
Keep on man!
Peace.