I read somewhere that the caffiene (sp?) can pass through to the bubs through your milk so while I was preggers I would only ever have 1 mocha a day, maybe a tea. Since DS has been born I only drink hot chocolate (although that does have caffiene as well). It is amazing how tasty decaf coffee is if you haven't had a real one for a while.
If you google caffiene you should find a caffiene calculator so you can see how much you are having.
Let us know how you go I am interested in knowing.