Everyone and every baby is completely different and you're doing brilliantly!
I found that once I put Blake in his own room (at 6 weeks) he slept much better. But that's what worked for us.
He wasn't sleeping very well during the day and was definitely over tired. HV told me to try get him out in the fresh air every day. So, after his lunchtime feed I would wind him then put him in the pram and take him a walk. (or sometimes I'd walk round the garden and up and down the drive with the pram) this works a dream. He'll sleep a good couple of hours which allows me to either sleep too or get some housework done.
Some days if it's too cold I'll feed him on my side at lunch and he usually falls asleep straight after (in our bed) and I'll try snooze with him. Then later in the afternoon I'll try take him for a quick walk round the block.
The fresh air really seems to help us (did a walk on the beach on fri afternoon and that night he slept 11hours!). Also I bath him by candlelight (our bathroom spotlights are far too bright) if he's not slept much in the day and it's late. And i put the hypnobirthing music on in the background! OH says it's like a frigging baby spa! I'll massage him after his bath too, keep everything calm and quiet and then feed him on my side in bed. The whole process is so quiet and peaceful that I figure he has no Choice but to sleep!
Good luck with it, you will find what is good for you both. Just try sleep when he does if you can - it's amazing how much better you feel. The sleep deprivation is horrendous. Xxx