fastasleep - I thoroughly sympathise. I also have large boobs and it is very difficult getting a large boob into a tiny new born's mouth ! Like one of my friends said it's like feeding him with a Big Mac (lol)
I just wanted to give you my support on this as you seem very committed to BF.
I have a DS now 11.5 months old and still breastfed. He is my first and only child. We also had difficulty getting a proper latch established for 4 days after he was born. He just would not open his mouth wide enough or suck properly. He just didn't know how to. It also did not help that my silly midwife (luckily I only spent 24 hours in the place where I gave birth and was counting the minutes to take my baby home) told me not to touch my boob, not even to help get it inside my baby's mouth. I agree that the aerola should not be touched or squeezed, but with a big boob you simply have to touch the boob to get baby to take a proper latch. You can end up with horribly painful nipples if baby ends up chewing the ends of you nipples all the time.
In fact you do need to have a bit of practice with a large boob, and don't listen to anyone who says don't squeeze your breast a bit to help get it into baby's mouth.
Also I had a natural birth and after about 8 hours of intense labour, I ended up with a very painful pelvis. Walking, sitting and holding the baby to breastfeed him while sitting resulted in total anguish, especially in the first week. It was my husband (an engineer so he knows alot about technical things !) who suggested I hold baby on his side on the edge of the bed, and prop one boob on the edge of the bed while I was kneeling on the floor with pillows under my knees. I have to admit this is not a very comfortable position for BF, but I had less pain than when I was sitting and it meant that my boob was well proped up for the baby to get a latch. It also helped that a close friend who had alot of experience breasfeeding her two sons, came to our house on the 4th day and showed me how to get a proper latch without suffocating baby !
After day 4 we never looked back. With practice the latch got better and better and he began to suck for 10 minutes, then 20 minutes and so forth. He had doubled his birth weight on exclusive breastfeeding by 4 months !
The other thing that works really well (and DS and I use this position 11.5 months later !) is lying side by side on the bed. Again the boob you are feeding from gets proped up by the bed and baby is nice and comfortable too lying on his side - usually sends him dozzing !
I am not a breastfeeding expert, and indeed I think that if my friend had not helped "undo" some of what I had been taught by midwives and the one NCT adviser (please no criticism of the NCT in general, just the one particular adviser), it may have all gone horribly wrong. But like you I was extremely persistent.
Please do seek some help from a breastfeeding adviser both before and after you baby's birth. The NCT taught me the basic methods of BF when I was pregnant and I didn't have a clue (they use dolls to teach you), but as I always say nothing beats a real life baby and a real boob being observed by an experienced adviser.
Do seek advice from several breastfeeding orgs. Also if you have a friend or close relative who has breastfed successfully, they would probably be your best advisers ! I think it's sad that the "art" of breastfeeding has to be taught to us by strangers these days. In the old days it would have been mothers and sisters and cousins who helped.
Best of luck and don't give up !