I'm BFing my 15 month old and just started back on Met. Not so much for an increase in supply (thankfully, mine's always been great) but for the fertility benefits. BFing my periods have been semi regular, but I O late (but hey, better than before which was never without clomid!) and have really short LPs.
Anyways, according to both my OB and LCs, Metformin is perfectly safe to use while BFing. And the LCs recommend it whenever they have a PCOS mom who is having trouble with her supply.
HTHs and good luck to you.
