The lactation consultant here bought me the Avent shields. They are great! They are a contact shield which means that your baby's chin and nose still have contact with your skin cause the shape is sort of oval. You can get them from the pharmacies and maybe supermartkets that sell Avent.
She said these were the best for newborns, and I didn't have too many troubles with it. I only had to use it on one side though as that was where the ulcer was. They are a pain to keep washed and carry them around with you, but if it means your baby gets to be breastfed, its a small sacrfice I reckon!
Good luck this time around, ABA will be a great help I'm sure