Weight gain question

Wanda • I am a 28 year old mom of 3 children! My boyfriend and I are expecting our last baby in February 2017! between is this will be our 6th and are very excited!!
Hello all! I am currently 16w 4d and have not gained any weight... I lost about 8 pounds in the beginning due to morning sickness but haven't had any since about 10 weeks... I eat like I should and do some mild exercise but is it normal that I haven't gained any weight? I see my dr next week and will ask but wanted to know what u ladies thought also! Thanks!