It is difficult to answer this kind of question with any certainty. Studies that have been done on this suggest that breast feeding can be a method of contraception
if you are less than six months out from your pregnancy, you are breastfeeding exclusively (i.e. not providing food or other liquid to the infant), and if you are not having menstrual periods. Under these circumstances there can actually be 98% protection from pregnancy. However, if any of these conditions are not met there is a very high likelihood of getting pregnant, so going forward it is not a good idea to rely on this. When you go see your OB/GYN doctor
for your post-partum visit I would strongly recommend you discuss this issue and what your options are. Many women will either resume birth control or even get an IUD at this time post-partum, especially since the further out from your pregnancy you are the less you will get protection from your breast feeding. Most OB/GYNs will discuss this routinely at the six week post-partum visit but given that this issue has already come up you should make sure you talk about it. In the meantime it is a good idea to avoid unprotected intercourse, and condoms are always a safe option.