OP I was a 36J for a while and managed to feed in a sling when DS was little :) She won't be suffocated, don't worry.
I really think you need to get to a breastfeeding group, ask your health visitor where the nearest peer support group, MILK or baby cafe gathering is. Even better, find a lactation consultant or breastfeeding counselor.
Also would encourage you again to repost this in feeding.
There are risks to formula feeding, mainly because formula is not sterile, and people too often make up bottles incorrectly. It also removes the "virgin gut" qualities you may have read about, because it is not the same quality of breast milk. Also, I believe, "Just One Bottle" looks at the fact that each bottle you introduce, if not done carefully, can reduce your supply, so is a downwards spiral to exclusively bottle feeding when you might have just wanted a bit of a break. So in that way there are the risks to your supply and breastfeeding relationship, as well as possible health effects.
Will possibly get flamed for that, but hey, its the truth.
Please get to a support group - they will be able to help you, even if you reach a point where you are set on stopping, they will be able to help you go about it in a way which is easiest and most comfortable for you both. And do get a sling, seriously.