The suggestion to call Lifeline was in response to you stating that the tribunal was going to occur on friday and you had no support. It seems that didn't happen so therefore it's irrelevant.
So you have the details of the order, what are those details?
Are you aware of what is supposed to happen?
https://www.mht.wa.gov.au/what-we-do/our-hearings/
Have you been to see a GP to conplain about the pain the injections cause? I'm pretty sure you could get a medical certificate stating that you are in great pain (and all the effects the injections cause) that excuses you from work or perhaps even attending the tribunal, though I'd be disinclined to miss it, because I believe it's your best chance to state your grievances and have things changed in your favour.
You mentioned you don't have an advocate, why is this? Do you have anyone willing ro support you?
You're talking about legal aid, and particularly that they were of no assistance "last time"; I would pressume that the treating team is giving treatment/s and suggesting treatment/s that are within the law, so unless you have some legal reason to oppose them why are you going down that path? Wouldn't an advocate be more help?
You state "they said all this terrible stuff about me" and "idk how i am going to prove it because it is my word against them". The point here is that it is definitely their word against yours and therefore it's up to them ro prove it if you deny it. As i recall, in tribunals you are able to deny things and apeak up as and when you see fit to do so. Importantly one must not make themself troublesome and be careful about choosing when and how to interupt and when to stay silent. Although it is an argumentative process (in my experience) it is not a court of law and you have a great deal of liberty to speak and state your case. Obviously the hope is that you convince the panel wirh tour argument.
I understand your frustrations with the timing of things and the delays in notifications you receive are justified, you should make a big deal about this at the tribunal and state that this is detrimental to your mental health and in a large way causal to your health condition. You can follow this line of thought and argue that without such awful treatment your condition would improve. It's up to you how much you empasise this.
At the end of the day it's your choice what you say to the panel and how you go about convincing them that what you say and what you're asking for is fair and reasonable, therfore it's crucial that you are clear about what you want. Make a few salient points and stick to them. Keep things as simple as possible and stick to your guns.
If it were me or I was representing, I would be researching the drug/s that you're being injected with and finding acceptable alternative medicine/s and treatments that you'd be willing to comply with. The more you are prepared to participate in your treatment the more likely you are to obtain a successful outcome. Having a friend/advocate/witness that can vouch for you and testify on your behalf will go a long long way to success. Also if that person is willing ro be a part of and participate in your treatment plan so much the beter.
I have so much I COULD say but there is only so much time and space. If only there were a way to speak to you directly...