Multi-part question

You can reduce your breast to almost any size you want, it is just a matter of scars, shape, and risks. Mastectomy is the extreme of reduction. Nipple grafting is certainly an option since the more you reduce the breast tissue the more the blood supply to the nipple is in jeopardy. The other question of breast-feeding is a separate issue since ability to breast-feed is not dependent of size of breasts although nipple grafting would probably eliminate your ability to do so. Have a careful and extended discussion of your motivations, goals, and options with a reputable surgeon and perhaps get a second or third opinion.