FMLA Question!!!!

I work as a Quality Assurance Technician at a Glass Factory. I am planning on taking 12 week maternity leave once my baby arrives. I got the FMLA forms as well as short term disability forms from my HR and got them filled out and returned. LUCKILY, I got a copy in the mail because my HR had not said anything about them to me... On the FMLA form it states that I will be out for 6 weeks, it even states the date that I should be expected to return to work. Well, this is no good because as I said earlier, I am planning to take the full 12 weeks that they allow through FMLA because I believe going back to work at 6 weeks is far too soon. 

My question is, is this normal and I will still be able to take the 12 weeks anyway or did they fill it out incorrectly and now I will be expected back at 6 weeks if I don't have another form done? 

Hopefully one of you have been through something similar or know what they wrote on your papers if you used FMLA..