FMLA Leave Help

FMLA leave grants you 12 weeks off for birth and bonding with child correct?  My work is trying to tell me I am approved for 6 weeks off after birth because that is how long my doctor wrote on my paper that I will be seen by her after birth... it was my understanding that you received 12 weeks total, hence, why I am working all the way until I pop so that I have the most time with my newborn.  Can they really only give you 6 weeks total under FMLA?