Hey RYn, I feel your pain!
My DS has been a shocking sleeper since day 1. Co-slept at night with us even from the day he was born as would just scream when placed in crib. We have reflux issues too.
What are his day sleeps like? They do say "sleep breeds sleep" and for the most part I do believe it. Until recently, we had real issues with day sleeping - only catnapping for 45mins and waking up screaming, still tired but unable to get back to sleep unless I laid down with him and satyed there for at least 30-60mins. I used the HAB sling A LOT as DS would sleep better in that and at least i got things done. It does bedome very drainign as they get older, however.
Have you thought of using a hammock? Wasn't a miracle for us but certainly heaps better than carrying him all the time. Your DS may feel more secure in the hammock, plus the element of movement is there even if your not ie when he stirs, the hammock moves. I am able to get my DS to sleep in the hammock bouncing it one handed whilst reading or using the computer with the other.
I do understand the lonliness of setling a baby on your own - My DH is not very involved either and I dread to think how many hrs I have spent alone in the bedroom bouncing, patting or BFing DS to sleep. MY DH did do the hammock bouncing a few times as at least it is not that hard and no "I don;t have boobies" excuses.
At 4.5mths my DS can now sleep in a cot (head elevated and sleeping on left side) and is relatively easy to settle with dummy in, wrapped and patting and/or stroking his head. The patting actually replaces movement as it is not the touch that settles him but the fact that the mattress vibrates when he is patted. I could "thump" the mattress itself and would probably work just as well. Not nearly as draining as rocking in arms!
Wish i could say he also sleeps through the night but we are still struggling - we have 2 feeds overnight plus a few other wake ups and sometimes over an hr to resettle especially around 3-4am.
I hope things improve a bit quicker for you!
My only other suggestion would be to try massage prior to bath as some bubs are stimulated more by the massage.
we do:-
quiet play
massage
bath
BF
story
bed b/n 7-7.30pm

Sorry for the long post but I know exactly how you feel and hoping something might help. Each baby is differet and you just have to keep tring til you find what works.
In the end, is co-sleeping for awhile longer a real problem? I would continue but DS now doesn't sleep any better in with us or not. I have the cot right next to the bed so I can stroke his head in a half daze!!