I can only offer my experience, as I tend to grow big babies, too, and passed the GD test with flying colors both times. My first son was 9 lb 13 oz and had mild shoulder dystocia. The midwife was able to maneuver him out, though. My second son was 11 lb 3 oz and was posterior. He was much harder for me to birth, but there was no shoulder dystocia. This time I'm hoping for a "small" 9 lb baby who isn't posterior. LOL
That said, I have fears, too, that I have a hard time putting to rest. Both times so far I have had retained placenta that had to be manually removed and both times I hemorrhaged badly, requiring multiple blood transfusions. I know that one is more likely to hemorrhage when birthing a large baby and I'm expecting that it will happen again (while hoping, of course, for the best possible outcome). I've spoken with my midwife about my fear of dying and not being around to raise my babies. She promises they will not let that happen, that they are very prepared and are expecting my particular complications. A C-section wouldn't really help me because there is also a greater risk of hemorrhaging involved and my body has proven that it can birth large babies. So for me I guess I worry about what happens after I give birth, probable retained placenta and hemorrhaging. My midwife said that the worst case scenario would be an emergency hysterectomy (which isn't desirable but certainly more desirable than death). She assured me that she didn't see that happening, either, though. I try to focus on what I can do to help bring about the best outcome. I tend to have low iron in pregnancy (the only time my iron is ever low) and have been taking supplements for a while now. I'm also having my iron levels tested more frequently than normal. Keeping my iron level up will be beneficial should I hemorrhage again. I'm also eating iron rich foods, cooking in cast iron, etc. I'm working on visualizing positive outcomes. It is hard, though. Like you, I kind of feel that my body has failed me. The reasons may be different than yours. But the effects of the perceived failure and the fear that it could happen again are incredibly weighty and difficult to manage.
My sister just had her 5th child, another home birth. She, too, has big babies (though none that were 11 lb.) and doesn't have my issues with retained placenta and hemorrhaging. I'm envious.
I've never had a baby that needed to stay in NICU and can only imagine how difficult that experience was for you, as well as the fear that it could happen again. I would try to focus on the factors within your control (such as diet) and then visualizing the best outcomes, along with relaxation techniques. Meanwhile, I know from experience that's much easier said than done. <3