Expressed milk temp

[Peachtree3]

Hi there, I'm fairly new to this site and also new to being a mum and would like a few more opinions on a debate I've been having with my mum.
I've been exclusively expressing breast milk for my ds since day 2 as he didn't latch at all (forceps delivery) and hasn't since.
I keep my milk in the fridge in storage bags and make up bottles in advance of when I might need them. The debate I've been having is my mum says I need to warm the bottles before giving them to ds as cold milk can upset his tummy, however he has always been ok with taking it however it comes, be that warm, room temp, body temp, cool or cold. We always warmed them at first but sometimes couldn't and he took them fine. Now most of the time his bottles are either room temp or cool, and occasionally being straight from the fridge.
I looked up the NHS website and it said its fine to give it to them cold if they'll take it.

Am I wrong to not always warm the bottles? Does it actually cause them digestive issues?
And another thing I was wondering about was my mum gave him cooled boiled water the other day to keep him hydrated and cool and he is 6.5 weeks old, is that too early for water?

Thanks in advance for any insight/help/advice.

Hi op
Not too early for boiled water and fine to give milk cold!
Congrats by the way.....it's tough at the start x

Thank you 😊 It's def been tough but I'm loving it.
And thank you, you've helped put my mind at ease that I'm not the only one that think so and that I'm just worrying haha. Xx

Glad to hear you're loving it. Take care x

Wow, only expressing? Just wanted to say well done! Temperature doesn't make any difference and cooled boiled water is fine, just not too much or he might not want milk as will feel 'full' because of the water.

Thank you! Yeah just expressing, I've managed to get a good supply going though so it's been better than I thought it'd be.

Breastfed babies don't need water, but you'd expect them to feed a lot more in the hot weather. Not sure about a baby that's being bottle fed EBM. I'd maybe just offer the bottle more often than you might in cooler weather.