Only 15 lbs

With my first pregnancy I had an emergency c-section cause my baby was big (9.13lbs). And with my sceond pergnancy I ask my doctor if I will have to have another c-section? She told me I didn't have to but I should only gain 15lbs with this pregnancy. So she has me on a diet and working out. My sisters and hubby is telling me not to listen to the doctor and eat what I want. Right now I can't eat everything I want right now cause I have really bad morning sickness but when I can eat I eat till I'm feeling full.  What u ladies think?