Hi @Annabelle I feel the same. I'm booked in for mastectomy and DIEP reconstruction at the end of the month. I spoke to my counselor and she said these feelings are completely normal. I think that even when you have trust in your surgeons and have answers to all your questions there's still an element of the unknown in that no-one can predict exactly how you will feel afterwards or what your personal results and recovery path will look like.
I have found the Choosing Breast Reconstruction group really useful and would second @kmakm that it may be helpful for you. You might also find the Reclaim Your Curves Facebook group a good source of support from other ladies facing similar circumstances.