Breastfeeding cause miscarriages?

Rebekah
Well i am still breastfeeding my 11 month old an I'm also pregnant but i fear that according to my blood work that my levels are not going up like it should an hormone levels are low too. Doctors office said it could be signs of a miscarriage but i have not had any symptoms of one. Other then a brown discharge here an there. I cant help but wonder if its because I'm still breastfeeding. What do you think? I am aware that if i lose my baby then it wasn't meant for me but i am wanting to try again. Which is why i feel i need to ask if you guys think it could be from breastfeeding?