Eat lots and lift heavy.
That's all there is to it man, forget about your test levels and creatine.
In regards to your knee, what lower body exercises do you currently do?
It depends on how my knee is feeling on any given day. The problem stems from how I walk. I just today got a new pair of custom-made orthotics and I'm really hoping they'll help. I had a pair made for me a couple of months ago but they weren't helping. So my podiatrist examined me and recommended having them altered. They just arrived about an hour ago and I'm not crazy about how they feel but we'll see.
If my knee is sore on a lower body workout day, I may do only one exercise for my quads: weighted quad leg raises (not really sure the name - it basically involves lying on my back with one leg bent perpendicularly and raising the other leg in the air and holding it). If my knee is up to it, I'll also do quad leg extensions. I know those aren't great mass building exercises but I don't think there is anything I can do.
I'm fine with hamstring exercises. So I deadlift, do hip raises, and curls. I would like to find more leg exercises I can do though. Lunges and squats aggravate the knee too much. The area I have tendinitis in is right below the knee cap - where the doctor hits to test your reflexes. It's developing in my other knee too, although it's not as bad.
I do also do some rowing on my concept 2. Depending on how the knee is, I may not do the full range of motion for the legs though.