Odd Results, Go Figure...

I’ve been working out for few years and got good results early on. Over last year or so stagnant. Started reading T-Nation and switched to full body 3 times a week with compound exercises. Been doing this for a few months and here is the odd thing. My clothes fit tighter around my muscles,my wife says I look bigger and I notice in the mirror that I look different. BUT I have hardly gained a pound. How is this possible???

Rob.