I'm sorry you are going through this OP, I've been where you are with my DS (now 2) and it was extremely tough. I remember reading the Sears high needs baby book and recognising my son in their descriptions, and feeling relief flood my body as I realised it wasn't just him.
I was so isolated in the end because we had to give up every baby class and I couldn't meet with my NCT group as my son would scream blue murder whilst their babies sat sweetly/just dropped off to sleep in their prams as they sat around drinking coffee. My son detested the car seat, sling, pram.
At home he could just about handle a baby bouncer and our glider rocking chair was my sanity-inducer, we would sit for hours on it. I can't bear to part with it even now. I found podcasts a godsend, some parenting ones but also some funny ones.
My mum did help a bit but had a huge project at the time and lived 200 miles away which meant help was limited. My FIL was dying (son was 6m when he died) and this meant my MIL needed mine/DH's help rather than anything the other way. She didn't understand how tricky things were and still makes comments now about me not bringing DS to the hospice enough. It was a 1.5 hour journey each way, I couldn't even take DS on a ten minute journey in the car without full on screaming. I don't think she will ever forgive me for not being there enough when 'off on maternity leave doing nothing' 
My little boy is two now and genuinely the light of my life. He is funny, interested in everything and adores all the classes and activities we jam into each week. His behaviour is brilliant (when out and about at least, somewhat more testing at home, in a typical two year old way!). One thing I read in the high needs baby book was that these babies can have some brilliant traits and good communicating skills. My DS has amazing language and communication skills now, people are often commenting on it. I like to think he just didn't like being a baby and has become increasingly happier since becoming mobile and able to articulate his requests, needs and feelings.
I hope you start to see some changes in your ds. I agree with pp on the outside support, I felt so much better when I got some time without screaming and could just drive the car without feeling terrified and traumatised in equal measure.
Be kind to yourself OP. This will pass. It might not feel like it right now, but it will.