Gods, yes, Christmas! If you're going to feel overwhelmed at any time - or your baby is - now's the time.
Hopefully things will feel better when the party season is calming down... :) But it sounds like you're feeling a bit more in control now, with more of an understanding of the normality of what you're going through.
I think the phrase "rod for your own back" should be removed from English :) In most countries babies are carried by their mums or siblings all day (NOTE: It's not all down to mum!), given free access to the breast (ok, that bit generally is), sleep with their parents and they turn out Just Fine.
I think you're doing a great job, and your baby is lucky to have a mum who is open minded and not to be swept along with convention, based on culture, not what humans have always done and what they do in most places outside the UK and US, and some of Europe. Our convention/culture comes from recent attempts to control child rearing which just haven't worked, rather than realising that babies don't read books or theories. They are what they were thousands of years ago and they're expecting to be born in a cave with Sabre Toothed Tigers roaming outside, and sticking with mama, thank you very much, is the very safest place to be right now.
Babies grow out of being high needs like they grow out of nappies. No one thinks they're making a rod for their own back by using nappies - it's accepted they'll just stop using them eventually (sometimes with persuasion, but that's also fine). It's the same with co-sleeping, nursing on demand and being carried. They just grow out of it when it's right for them, and move on to their next stage without a look back while you stand there, having gotten used to all this, and feel sad for the sudden move they've made away from you! That doesn't need to be just yet - it will happen soon enough and I promise you you'll wish it hadn't happened so fast, intense as it is now.
I quite often post this quote from Dr Sears which I love. His work is great - very supportive and informative. He says, "Babies will wean and someday they will sleep through the night. This high maintenance stage of nighttime parenting will pass. The time in your arms, at your breast, and in your bed is a relatively short while in the life of a baby, yet the memories of love and availability last forever."
I know it's hard, but you're not alone and hopefully some of the strategies here will make it a bit easier for you.