My ds is almost 10 weeks old and has got into quite a routine of feeding and sleeping at 7pm, then sleeping till about 2 or 3 am. I want to start excersising again but --can't be bothered-- don't want to express and get him used to bottles. I want to start exercising and go swimming to lose a bit of baby weight. AIBU to go swimming (out for about an hour and 15 mins in total) without any back up milk for the baby?
Put it this way - will you be utterly devastated if your DS has to have some formula? If the answer is no then don't bother expressing. It's not likely to be a regular thing and it will save you lots of faff.
If it does matter to you then try expressing from one boob whilst you are feeding with the other after your DS's biggest sleep, even if you only do it for a few days you will have enough in the freezer for emergencies and you can stop bothering with it after that!