Do formula fed babies put on more weight than BF?
As a general rule, the BF bubs gain faster when newborn, but the FF ones overtake at about 4-5 months and grow bigger from then on.

Adele - I agree with Kellxx, try a natural energy boost like fruit as opposed to caffeine... it should give you longer lasting energy as opposed to an instant rush. Another thing, do you eat enough carbs? Without enough, you will run low on energy. Even Milo might get you feeling better again.