Nanny I have some odd experience I can share if you like!
DS was 4wks early and had no suck reflex, double tongue tie, and jaundiced, so was bottle bed Aptamil for the first few days.
We then moved on to a combination of expressed breast milk and formula, still bottle fed, but constantly trying to get him to latch. Awful, and v unsuccessful.
After his tongue ties were snipped and he got a bit stronger, his boob latch started to improve. From 1 month old he was almost exclusively BF, with the odd bottle of EBM.
Now then....... For me, mostly due to DS's awful latch, it was agony. I also had constantly recurring blocked ducts, which were like passing razor blades, tho they were actually teeny tiny little grains of solidified milk working their way out.
I spent most feeds gripping the floor with my toes, or watching the subtitles on TV to distract myself from the pain.
Feeding became easy at 4mo, but because of my duct problems, the pain didn't completely stop until 9mo.
I fed DS until his 2nd birthday, partly out of sheer relief that it was finally pleasant.
Regardless of all the difficulties we had, and the fact that the early months were hellish, I'd absolutely do it again, and am planning to with DS2.
However, this time we will book the lactation consultant to visit ASAP after the birth, as DS2 is likely to have TTs too, and I'll be going to the BF clinic every day week until all is well.
If however it doesn't work out, I will FF. With DS1 I regarded BFing as my job, but this time, I have both him and the new baby to consider, and frankly formula feeding is soooo not the end of the world.
If I end up with PND again, FF will allow DH to help with feeds, and I'll be able to rest more. Sleep deprivation is sometimes compounded by the more frequent feeds a BF baby needs.
From my point of view, even with all the trouble we had, BF is great - free, comforting, always there, and definitely what I'm hoping to do again.
Just always remember, it really doesn't work out for everyone, and it's nobody else's business how you feed your baby! I can't stand the 'Breastapo' attitude that everyone can and should BF, it's simply not that easy. In an ideal world we all would, but, I don't live there.
Re the saggy boobs thing, I've read quite a few things that say it's pregnancy that damages the breast tissue and makes then saggy, so even those that FF from birth could still end up with the tennis-balls-in-socks look! I'm not convinced that's true, but hey.