reread the post by "Loved" - it makes a lot of sense!
I am exactly where you are. DS was huge, 15" head, malpositioned, interventions, section. Now with DD due in Nov, I have the same thoughts and worries. Yea, she will also be big (I am 5'4" DH is 6'4", and we have proportionally large heads). I think the issue is not the size, but the position, which you know already.
1. So, you could end up with big baby again, but better position, pressing nicely on the cervix, and therefore a much smoother, easier labor. Happy homebirthing in that case.
2a. Or you could end up with a malposition again. In which case, what are you going to do about it? Think about options you could take (spinningbabies.com, rebozo, polar bear...) to change the position. With proactive mesures, the baby could turn, and again you have a hppy homebirth.
2b. Or, even after you have tried, baby still doesn't turn. Then think about what YOU want. This could mean giving yourself more time, this could mean transfer and have a cesarean, this could mean anything in between. What is important is you try, but that you don't kill yourself in the process. Respect your limits and boundaries. Make the best choices you can at the time and you will feel good about your decisions. None of us are perfect, just human.