I agree with Karen, although I think you should check your Iron levels too. Especially if you are having a much heavier or longer flow. Just be very careful not to overdose and remember to count whats in your food and all your other vitamins. Maybe right before TOM and during it you could try to include some extra red meat? Maybe call your OBGYN and ask?
I think Karen is right though, once you get where you want to be and settle into a rythm I am sure TOM will even herself out too.