In general, you should avoid any birth control that has estrogen. This can significantly drop, alter, or even diminish your supply. Because of this, your options are limited to the mini pill, the copper IUD, condoms, or natural family planning. The Mirena is supposed to be okay for breastfeeding mothers - but be aware that there is some circumstantial evidence from mothers whose supplies disappeared overnight with it. Breastfeeding can be used in conjunction with natural family planning, but there are very strict requirements in order for it to work. This is called the Lactational Amenorrhea Method (LAM). You can click here to learn more about this. Just continuing to breastfeed is not enough to protect pregnancy. Click here to learn more about breastfeeding and birth control.