I am particularly interesting in when you knew your B2 levels were correct? I am not talking about lab values, but more specifically when your body positively responded. For me, different vitamins have different tells - P5P (B6) - I know I have enough when I have vivid dreams consistently and I don't have any foot tapping/waving or RLS. Methylfolate (B9) - Oddly the most consistent way is when my sinuses clear. When its really dialed in it's like my head is cleared even in the deepest parts of my sinuses. I don't hear this talked about hardly ever, but if I had to guess its due to the reduction of inflammation in the sinuses.