In my opinion, to respond to your OP- no, I don’t think you’re being unreasonable to think your child is difficult. A number of your observations of him highlight things that are challenging to deal with, just on a basic human level.
I have one very tricky child and another much more chilled out one. The contrast is stark and was noticeable from very early on. When I’m dealing with the rumblings of guilt about not enjoying interacting with my tricky one, I remind myself that it’s nothing personal to them and I’m only human. I don’t like being shouted at, I find oppositional conversations exhausting and the noise and frantic physical movements (sensory seeking), set my nervous system on edge. Over time, my body has been primed to be highly alert to brewing meltdowns so I can never really relax when I’m around them. That’s hard to say, it doesn’t mean I don’t love them, but it’s my reality. The fact of it is, those behaviours are intense and they have a knock on effect to e.g. my ability to keep on top of housework or motivation for anything beyond just ‘getting through’ the day. Therefore, it’s not just the behaviours themselves, in the moment, that are difficult- it’s the domino effect on everything else.
I hear what you are saying about ‘nothing works’ and that, for me, was the phrase that made us explore what was causing some of these behaviours. It was also helpful for me to realise that my other child seemed to be well-adjusted (for want of a better term), so I must have some ability to be a ‘good enough’ parent.
Talking about my experience only- when we looked deeper underneath the surface, questions about neurodivergent traits served as a lightbulb moment to me. It hasn’t changed any external outcomes but, if nothing else, has validated to me that I was right to find things tricky. I was right in crying with exhaustion because things were so hard, everyday. That going out was harder to make a success because their brain processes things in a totally different way- it wasn’t/ isn’t just me being a crap parent. It isn’t just me not being cut out to be a mum. The assessment process helped me to organise my thoughts about a very, very complex set of triggers, sensitivities and behaviours. I’m not sure I can say it’s made things ‘easier’ but I would say that any opportunity to take a good look at what is going on is a positive. A diagnosis is arguably neither here nor there, depending how you look at it. But a better understanding of what is making things challenging is valuable (for the whole family)- hearing tests, really exploring the communication difficulties etc can all be a part of it.
It sounds like a difficult situation for all involved and your feelings around the behaviours seem completely valid to me.