loosing to much weight

Ashley • Baby girl born April 20,2016 #A.A.O
So my daughter is going to be 4 months on the 20th. I'm a breastfeeding mama n only give her maybe 2-3 bottles of formula a day or less. Now after giving birth I was loosing weight n I was happy. I got to my pre pregnancy weight but now I'm a little under it!!! I love breastfeeding but I'm loosing to much weight! Idk if I should stop breastfeeding or what to do. Any advice is welcomed 
July 24th
August 13th