C.M.
Sorry, but do NOT listen to the person who told you not to take birth control while nursing. Unless you're willing to use a condom every time you have every possibility of getting pregnant. If that's what you want, cool.. but if not then I wouldn't listen to that one. From what I have heard breastfeeding is only a viable form of birth control under certain conditions and for the first 6 months.
I have been told that a combo pill isn't great for nursing but there's so many out there that maybe there's a combo pill out there that wouldn't hinder it. I have heard that nuvaring has hindered supply (a friend has tried it). I had Mirena while I was breastfeeding and it worked just fine. You could also try the non-hormonal IUD called ParaGard or possibly Implanon (arm implant) but I'm not sure if that can mess with supply or not. Mirena is 5yr protection, ParaGard is 10 yrs (I think) and Implanon is 3 yrs.
I'm not sure about other options, but if you talk to your doc about it they'll probably be able to make some great suggestions!