Pregnancy and breastfeeding?

Mar • Hi, I`m 27 years old. I`ve had 1 miscarriage in 2013 and a rainbow baby in 2015. Expecting baby #2 October 2016
Anyone else pregnant while breastfeeding? My nurse said I can continue to breastfeed but she said that my milk supply will stop sooner or later. Has anyone experienced this? At how many weeks? Anything that can be done to prevent it?