Oatmeal,
Thanks for sharing your birth story. And yes, I can still hold my poop in!! I am guessing you made that comment because the OB told you you might never be continent again if you pushed out a big baby. BS!!! I am very continent, an can even hold my pee in!!

My son is almost 9 months old and I feel fully recovered, and have so, for many months. I only had one tiny tear and two skidmarks (not tears, but tiny something else). Recovery was so much easier having pushed out a big baby than having one cut out of me, that's for sure.
Trust me, I have read all the studies and there is no medical indication for induction to avoid a big baby. It doesn't make your labor any easier, and it is a risk for you as a mother, and a risk for your baby. Induction is just not good!!! You can push out a big baby, your body grows a baby that you can handle, trust me. I am speaking from experience.
I am on the national ICAN email list and I can't even count the # of women there who were induced at 38 weeks to avoid the big baby, and now they are at ICAN trying to heal emotionally and physically from the resulting cesarean, sometimes with a baby in NICU because they were born without being able to breathe well (a result of being born too soon and also a risk of a cesarean). I highly recommend this list, go to their website and you can get on from there, or PM me and I can give you instructions if you need them.
As far as your birth went, I know you did what you felt you needed to do. Sounds like the castor oil started your labor pretty well. I have heard that castor oil inductions can make things a lot more painful than natural labor.
And with an epidural, and in the positions you tried to push in, it probably made things harder for you. What would have been ideal is if you were unmedicated and pushed when your body told you to, in the positions that felt best. When I had my son, I told my midwife when I was pushing, no one told me when to do it. She gave me some pointers, that helped, but I just couldn't stop pushing during contractions. And I wasn't on my back, I was sort of on my knees, wiht my legs open, and reclining back (I was int he water, this is not a position I think I can get into on dry land) Oftentimes in a hospital, you are rushed. Your OB is supposed to be there, and they get a little impatient, maybe they don't want to wait around for hours waiting for your baby to be born. Much easier to scare the mother into thinking that she can't do it (and they would know, they are the supposed "experts"), and since she is likely exhausted, most likely she will agree.
I know how it goes, even though I never labored with my daughter. I took the advice because I thought that it was the safest thing for my daughter. I know better now. I have learned so much and it has made me somewhat cynical of hospital birth in general, unfortunately.
I knew, by the time I got pregnant with my son, that women had had larger babies than my daughter. Not many of them, that I knew of, but I knew it was possible. For example, my friend's husband (a big guy) was 13 pounds, and he had 4 older brothers that were 12 and 13 pounders too, 30 plus years ago when births wereen't so micro-managed, and Leilah, the owner of Birthlove.com, had a 12 pound 5 ounce son, unassisted, and after having a cesarean too, and there is a birth story on plus_size_pregnancy who had a 13 plus pounder after a cesarean too. I have no doubt that you can do it too, given time and REAL support, not "have the baby by Monday or get induced" kind of support.
Trust your body!!