Breastfed first and hopefully this one too. It was really important to me and I do feel that I didn't enjoy the first 8 weeks of his life as much as I could have because I was in a lot of pain feeding. I put up with the pain because the thought of bottle feeding did upset me, but I really couldn't explain why at all!
Re expressing you would do some before you went back to build up a supply but then would only express when at work for the next days feeds while you were at work. I went back when DS was 6 months and I had to express twice a day to make his one 9oz feed he had with the childminder and fed him before I went to work and before he went to bed, I started to wean him before I went back to work around 5 months so he was eating quite a bit of other food by then. At weekends I didn't express at all.
I can see the point about factory processed food, not just having formula as DS never had it, but as they get older they do eat more crap but you still have a choice over most of the food they eat and they don't need to have chicken nuggets for tea every day.
As I said I couldn't explain why breastfeeding was so important to me but I can say that once established it does save so much time sterilising, making and heating bottles. You can go out without taking loads of things with you, I did loose a lot of weight whilst doing it and you can do something at the same time as you have a free hand, not to mention the money you save! And no-one else has mentioned how relaxed you feel, a fantastic way to de-stress
I have to say that most people do formula feed, although a lot try breast feeding, it's true there aren't many who say they are going to formula feed out of choice. I found that I was the only one amoung my friends who breast fed and although I'm sure it wasn't intended their feelings about not breast feeding and how they were made to feel guilty was projected onto me and made me feel bad for breastfeeding to the point of not talking about it at all! I really beleive that most of their feelings of guilt were their own and that most health professionals accept that most mums formula feed and as most other mums do it too there is really no-one to make them feel guilty. I would also like to dispell the myth that the baby has to be permenantly attached to your boob as was mentioned before. My son fed roughly every 3 hours from very early on, had 1-2 feeds a night, slept through from 14 weeks and never used it as a comforter.
I would not judge others for what they feed it is your choice but it can be difficult to understand where other people are coming from with many aspects of childcare.
I found it difficult at first to feed in public because of most peoples attitudes, including my family. You only have to look around to see we are a bottle fed culture and that it is more socially acceptable.
For those worried about it I had thrush and mastitis and still fed until 15 months. I would say get the right support (midwives and health visitors are not always the best trained), go to a workshop beforehand and be informed. If it is really important to you then you will do all you can to breast feed and with the right support will succeed with the correct help. It isn't always difficult, although it was for me in the beginning but there are very few women who physically can't breastfeed so go into it with a positive attitude!
None of this is meant to be offensive just my opinion of what I have seen and answering what others have asked, I wish everyone luck with thier choice of feeding.