Moving a BF baby over to a bottle

[Newbie39]

I have to go back to work in a couple of weeks. My DH is going to be a SAHD but I desperately need my DS to start taking expressed milk from a bottle. I am having a really tough time getting my head round it.

1. How much should be in a bottle for him? I know he might not drink all of it and that’s ok but realistically how much would a full feed normally be for a 10 week old?

1. How often can I pump without making it so I don’t have enough milk for him when I want to do a normal feed?

1. How do we warm breast milk when we are out and about? Everything we have seen says it must be warmed slowly and gradually and our bottle warmer takes 10 min to warm plus 15 minutes cool down.

1. How do I keep my pump sterile when I take it to work?

I did this too.
We used the Medela breast pump and bottle system. Each bottle was 150ml. I’d pump into the bottles and then unscrew from pump, refrigerate and then DH could simply screw on the nipple attachment to the bottle, reheat, shake and feed the baby.
To train baby to bottle...I had to leave the house so that DH and baby were alone during a feed time...so a good 3hrs. My babies knew if I was home they could scream until they would get milk from the source..my boob. Only by me leaving did they accept the bottle. So, I’d go and pump and come back. Good practice.
I would pump in morning after am feed before going to work. So pumping around 5am, at work at 6 am, then I would pump at 9am, 12am and 3pm and then home around 6pm. I pumped as much as I could for 15mins each time. Aiming for getting four full bottles a day at work. I would also pump on weekends now and then and freeze the milk in little plastic freeze bags (medela makes them) to set up a breast milk stash for days when I had to skip a pumping session or I pumped but nothing or only drops came out. So DH would use the fresh stuff first and then dip into stash if he ran out. Try and build your stash a bit before going to work.
DH had a bottle warmer that plugged into his car. He’d take milk in a cool box and then warm it that way when they were out and about. If “we” were out and about..I’d just breastfeed not use bottle. The pump isn’t good at stimulating milk supply so you need to breastfeed as often as possible when not at work.
The Medea breast pump I had was sterilised by first washing all the bits and tubing, then you shake off the water and put it in a microwave proof bag and microwaving it for a short time. Then packing away until next pump.

Before you go to work, only pump AFTER the baby has finished feeding for up to 10mins. Now, I tried a shortcut...my baby would feed from right boob, then left boob & fall asleep. So I’d pump from right boob while baby was on left boob. Then both once baby was asleep.
Ok, it worked BUT by not keeping things equal my right boob proceeded to grow to be a cup size larger than the left boob. So that was an unplanned side effect. With later babies, I just waited until they were done feeding and then pumped from both boobs equally.

Cannot help much on the expressing for work issue, but wanted to say that we have always given DC expressed milk cold (usually within 5-10 minutes of taking it out of the fridge). A friend had twins and while in sbcu the nurses said if the babies are used to milk being cold then they will accept it that way.