To feel unsupported and misunderstood by work

The thing is you're expecting a lot from them after only 6 months and in your probation period. And presumably everyone else there had to manage under the same conditions/training and this wasn't set out just to target you. It seems like the completely wrong job for you. If it's causing you this much stress and anxiety in only 6 months can you not see that you aren't suited to the job. I don't think the company owes you anything actually.

I would be picking up part of their admin workload if my suggestion was picked up on.

You can't insist on changing someone else's role to suit you better.

I've also done extra emails and bill workings in the overtime I've never demanded a penny for!

Well that's just daft. Why are you working for free?

You sound like you’re really struggling, and I’m genuinely sorry about that.
You’ve got to lose the mindset that you working overtime and weekends in order to complete your job requirements is in any way beneficial to your team, though.
It’s unsustainable and shouldn’t be necessary at any point.
Certainly not at six whole months in.
It’s not going to get any easier for you, is it?

You shouldn't be working in the evenings and weekends. You don't get paid for that.

The thing is, OP, you can decide what you think is best for you.

What you can't decide is what is best for the company. You think that your employer will be much worse off if you fail probation and they are a person down. They may be thinking that they don't want to saddle themselves with a problematic employee who has somehow passed probation despite not being able to do the job.

Best case scenario for you at this point would probably be an extension of your probation period. The more likely option is that they will terminate before that. Unfortunately, it just doesn't seem like you're suited to this job. And yes, if you're neurodivergent and/or struggling with your mental health etc, they need to put in reasonable adjustments. The difficulty here is that the types of adjustment that you're proposing really don't sound very reasonable.

Also when I am picking up part of their workload short term to help them long term I don't see how I'm being selfish or unfair.

Maybe the rest of the team don’t want you taking the admin off them, because they want to keep the mix of tasks that they signed up to? The calls works sounds the most intense part, from what you’ve said. So if you do less of that - somebody must be doing more of it.

Hold on; you’re picking up part of your colleagues work load to help them out?
What??

Why are you repeatedly not answering how long you have been there?
edit: we’ve literally posted at the same time and you have now said

Have you actually not been given enough training on the products and procedures - or do you need a longer period than most, do you think, to understand them?

Also reasonable adjustments aren't about what's "fair" to the rest of the team. It's about what can be done to enable disabled people to function and work to the best of their ability and even the playing field.

You sound like the adhd part of me. With reasonable adjustments in place, i outperform most of my colleagues. Without reasonable adjustments, i was really struggling.

They do not need to ask you about a doctors appointment, in fact they should not. It is your responsibility to tell them if there is a problem that affects your work.

In comparing yourself to someone who has been off sick and then had a return to work programme, I’m afraid you’re not making a like for like comparison. You’re on probation, that’s the time you have to prove you can do the job. Employees who have completed probation, and then at a later stage go off sick, it’s worth the company putting more effort in to their return to work. They’ve invested in them and they’re getting them back to their high standard. You haven’t proved you’re capable of that standard yet.

Im afraid I think that, while it doesn’t necessarily sound like the best managed place, I think your expectations are too high. Personally, I would do more than your manager has, but I do not work in a high pressure customer facing environment.

And how has the team benefited from these sacrifices?

If you think you may be neuro divergent, then your workplace may have to put reasonable adjustments in place even if you aren't diagnosed.

Ask for a referral to occupational health and speak to your GP , to get on the waiting list.

Think about what reasonable adjustments might look like for you - for me (adhd/asd) if i was in a call centre it might be longer/more breaks, more time allowed for training, flexible working, and more time allowed in call wrap up off the top of my head.

What sacrifices?

It's not a pressure cooker, it's a job you're not able to manage successfully. That's not your employer's fault in this instance. You need to find a new job.

Do they know you have been to the doctor with stress though?

you have mentioned others getting accommodations, yes that makes total sense if they have been there for years but if you are a new employee then that is different.

How long have you been there?

How long have you worked there, op?

I’m sorry but they can’t accommodate you in a job which is not suitable. It would be like a PA getting accommodations and doing just admin in a lawyer‘s role. You need a new job.

I manage a team in a sales/customer service environment and unfortunately there is a base level of pressure, which sometimes can be high, that I am not able to remove. It just is that pressured, and people can either manage that, or they can't. That kind of work isn't for everyone.

I'm always happy to help people manage their workload, plan their time etc, but what I can't (and won't) do is remove parts of the job to make that happen. I'll help someone manage their workload, but I'm not re-distributing it. Somethings just "are," as awful as that maybe is.

We call it "phone fear," and to be honest once people have it, they're usually not around long.

How long have you been there?

What is the job?

Do you think you will be able for it given time?

Are your colleagues doing the same work in less time?
The overwork was hardly for the team’s benefit, there’s little benefit to anyone in you not being able to do the work in the allotted hours, especially when everyone else can.
You still haven’t said how long you’ve worked there, are you still on probation?