My 10 week old is sound asleep on my chest at the moment after waking for a feed. I'm about to go back to sleep. He sleeps from 9pm to 9am, waking every 3-4 hours for a feed. I sleep brilliantly.
The solution? Co-sleeping.
I tried everything you've mentioned in your OP. My baby would absolutely scream inconsolably when put down. He hated swaddles and he refused to sleep on his backs. I was so sleep deprived for the first 3 weeks. My partner and I took it in shifts to sleep. It was utter miserable hell. Then my partner fell sick and so did his family and my family all at once. It was ridiculous. I was alone without support as everyone got sick at the same time with fevers.
I cracked at week 4 and brought him into bed with me. It's been pure bliss ever since. I literally changed as a mother over night. Before that I was feeling upset and angry and dreaded every single night. Some evenings I was crying just at the thought of the coming evening. It was torture.
Now I wake easily, breastfeed him, cuddle him, and we fall right back asleep together. All he wants is to be with me. I truly wish I'd done it from day one.
We have a next to me cot that sat abandoned until just last week when I bought a Done By Deer Cosy Nest. Sometimes he sleeps in it in the bed with us. Sometimes he sleeps in it in the next to me crib.
You have to make your own decisions weighing up the cot death guidance. But honestly I felt it was far more dangerous for me to be as sleep deprived as I was. You can research safe co-sleeping methods. Even the cosy nest I bought isn't recommended but I trust my gut that I've got everything set up in the safest way possible.
My baby is a million times happier and so am I. Now I can enjoy him. I still feel guilty that I didn't listen to his crying those first 4 weeks and realise what he was telling me: I'm not happy, this isn't working.
But you live and learn. They are tricky little mites to figure out.