If you want to get bigger again, add more carbs (post workout, on workout days only) and see where that gets you. So long as you avoid gluten and sugar (i.e. bread, pasta, desserts, HCFS, processed food in general...) you should be able to gain mass without messing up your digestion and health. If you're still doing a ton of basketball and plyometrics while being that lean, you are def. going to catabolize your muscle if you don't go heavy on calories.
These days, I eat a fair amount of sweet potatoes and potatoes, and I've always eaten lots of tomatoes. Throw them all in a stew with plenty of meat, onions and garlic and you will have clean fuel for days. Or add more rice along with your steak and eggs. You have a lot of latitude to play around with gluten/sugar-free carbs since your body fat is low and you are exercising a lot (i.e. your insulin sensitivity should be pretty high right now). The key is always to match it to activity level, and then eat EXTRA to get to the extra size you want. If all that fails, and you are prepared to risk getting a little flab along with muscle and strength, start chugging the milk! I would proceed with caution though, 'cause you're definitely healthier with low body fat like you are right now than you would be with more muscle, as much fun as muscle is. My advice would be to ramp up the carbs gradually, no more than one meal a day for a couple of weeks. That way you can get a good handle on how much of an effect it has.
