c-Section? (sorry so long)

So, at my last ultrasound I was told my baby is large. (I believe she was measuring 4lbs at just under 31weeks? it's been a while). Anyways, I have a past injury - broken sacrum and shattered pelvis. I had my first daughter after the accident, but the doctor who delivered her said I never should have had her vaginally. (I did, without complication, but it was a very easy smooth birth to a 7lb baby at 21 years old). The current doctors say if baby is 8lbs or close to 8lbs, she would recommend a c-section to be safe, as I am older, baby is bigger, and I was lucky first time around. but, she says regardless of size, due to the fact that I have such an injury in the past, I definitely have that option to consider either way, but also due to the fact that I vaginally delivered one baby, I have that option as well. I have no idea what to do if they say this baby is as large as we think. I don't want to risk pushing forever then having a c section anyways... but i am terrified for a c section and making that decision! I hear it's harder to lose weight. I'm scared it will mess with my breast feeding... I'm terrified! My mom has only had c sections. she says they aren't bad... I'm terrified. advice? your experiences?