11 weeks no weight gain is this normal ?????

Danielle • Im a mother of two beautiful little girl Jaidyn Rosalie age 3 born July 4th 2012 and Ryleigha Ashlynn Marie age 1 born August 5th 2014 ... Now I expecting another baby some times in July 2016
Hi I'm just wandering if anyone else is in this boat!! I'm pregnant with my third child and generally the more kids you have the more weight you gain well I have been 134 pounds since I found out I was pregnant I have not gained a single ounce of weight just wondering if this is normal and if anyone else is going through the same thing I'm so excited to have a baby bump being pregnant with my third child and nothing anyone have similar problems