I wouldn't worry about counting calories right now. Your baby is only 2 months old. He will increase his milk supply by nuring more and longer without you having to worry about using a breast pump. By now your supply should be sufficient to take care of him without any outside supplements. As for exercising, you will using extra energy up that would be used to make milk. This also goes for housecleaning. Ever have a burst of energy and want to clean only to find that half way through it you wondered why did I start? It's because you are producing milk. If you eat proper meals daily your weight should come off because your body is making milk.
I ate good sized meals without any junk and had a bottle a beer a day while nursing (brewers yeast) and when summer came, I was back into a 2 piece swimsuit without any extra fat. My neighbors were envious and I didn't do exercises just did normal housework and chased after a 3 1/2 year old. It is after you stop nursing you need to watch what you are eating and exercise more.
My skin was the clearest it had ever been while I nursed because of all the extra liquids you drink to make milk. You must remember it took you nine months to loose your shape it will take you about that time to get it back.
Enjoy this time in life as they grow reall quickly and this will be a fond memory.