Are you having immediate reconstruction after the mastectomy? I think if you are then it's more painful but remember that there are really good drugs for pain management. I think you may feel better once the surgery is behind you because it will be over and not something big and scary that's just around the corner.
I had bilateral mastectomies - that's definitely more painful than a single mastectomy. I personally know people who have had a single mastectomy who have told me it was not painful and they recovered quickly.
Just keep expressing your fears - it's better to do that than keep it all in. You WILL be okay Jodie.
Sending more hugs,
Xxx Jeanine