I'm leaving this post open for now, but if it gets ugly .I'm locking it.
Please look at all the facts about breastfeeding vs. formula, not just sagging. Weigh the options and decide which choice is best for you and your baby. For example:
breastfeeding pros:
~it's free
~your baby has a better chance of fighting off infections, avoiding becoming sick, etc
~no bothering with making bottles, running out of formula, finding a formula that agrees with your baby
formula pros:
~no pumping
~others can feed your baby (without you pumping)
~no sore nipples
~no restrictive clothing/bras and no need to worry about breast pads and leaking
.These are just a few examples. I personally opted to breastfeed my daughter, and at 9 1/2 months she still nurses. She's only been sick once, and we saved a bundle of money that would have been spent on formula and bottles. I'm able to sleep very well at night without having to get up at 2 in the morning to make a bottle - I just pop a boob in her mouth. I decided that my child's health is more important than my boobs, which will sag regardless of what I do.
But again, you should make a decision that you're comfortable with. Decide what you feel is best for you and your baby, and stick with that. Good luck.