Anyone else enduring the four month sleep regression?

[Orangelover]

Baby DS 4.5 months until this week was a champion sleeper. Barely gave us any trouble as a newborn and always did long stretches, has slept through pretty much for the last couple of months and went down beautifully at night in his cot between 8 and 9pm

UNTIL this week. Oh my goodness this four month regression business is slapping me round the face good and proper. He woke multiple times before midnight, was really hard to put down and was sleeping so lightly every tiny noise had him awake. He then did manage a stretch until 3 but ended up in bed with me from then which really isn’t my preference as I don’t want to co sleep but just couldn’t stay awake long enough to ensure he was in a deep enough sleep to transfer him.

The only thing that will settle him back to sleep is the boob. DH tried rocking him and swaying him for ages but he was having none of it.

j know all of this is normal but is anyone else going through it as well? I think it feels particularly awful because we were doing so well!

Totally normal. And it's nothing you've done or not done - don't congratulate or berate yourself! Baby sleep is almost entirely biology and temprement.
I would set yourself up so that if you do fall asleep with him, it is as safe as possible - eg don't sit on a sofa, no bedding nearby, ideally just you and baby in a firm clear bed, or if your partner is there, don't have the baby between you. Night feeds are normal and necessary at that age - they are growing so much. Just give boob if it works. I'd consider later bedtime that aligns with yours, so that his longest stretch is when you go to bed.