If I recall correctly from Chayei Adam and elsewhere, if you're in the middle of a bread-based meal and excuse yourself to defecate, first of all you should wash with soap and water for hygienic ...
How many slices are required to make you responsible to wash on Pizza?
If you wash your hands and your mind goes blank and you dont remember if you said a bracha or not. do you make a new one? Do you wash again and then make a new one?