Struggling to get 3mo to sleep on his own

I am really struggling with my baby and feel like I am doing everything wrong. I’m not sure if I already set us up for failure, but I have an extremely fussy baby who absolutely hates sleeping on his own. Our routine is we try to have a feed, swaddle, sound machine, heating pad, and shush and pat his chest every night after bath time at around 6-7pm to get him to sleep. And it’s this battle for about 5 hours every night where he would fall asleep in our arms and as soon as we lay him down he starts crying. There’s been times where I’ve been able to settle him while he’s in the bassinet and I just pat his chest and he would fall asleep only to get up in ten minutes. And not to mention he gets himself so worked up he starts sweating. I only have him in a short sleeve and swaddle. I eventually give up and have him co sleep and sleep on my chest. He doesn’t even settle easily in my arms, I have to wear a carrier, wait for him to fall asleep, and slowly remove the carrier while we are in bed and hope he stays asleep. He only takes naps in the carrier during the daytime. He settles easier with my husband and he doesn’t need a carrier with my husband he can just sleep in his arms while my husband is on his computer etc.

There’s only been one week where he’s actually slept through the nights in his bassinet (waking up every 4-5hrs) and after that week it went back to this craziness.

I am just struggling mentally with this because I can’t even move in my bed or scratch my arm without risking waking up my baby. And he is always fussy whenever we try to have play time or read a book, it just seems like he just wants to eat and sleep. He’s also just overtired most of the time because we try for hours every night with the bassinet until we are all exhausted.

I’m sorry if this post is all over the place. I would appreciate all the kindness and advice. Should I start sleep training? I’ve asked my pediatrician about navigating through this and he basically just told me to suck it up and he remembers his wife rocking their baby for hours every night and parenting is hard etc. I’m really not sure what to do anymore.