Can I appeal my CAGs?

My UCAS predicted grades were BBC, but my CAG's came back as CDD. I've been having a tricky time throughout the year, my school is aware I'm a young carer and have suffered from persistent ill health (and taken 2 weeks off for an operation + recovery), even asking me to write a timeline of how it's affected me for their assessment. I spent one set of mocks up all night and drastically ill (I had a benign tumour that at the time was starting to destroy my jaw bone and gave me the flu x10). There are witnesses to me sitting my exam with my eyes streaming and putting my head down made the pressure much worse, so I struggled to concentrate.
I pulled through and got CEE in my mocks. Not fab. I was now attending upwards of 8 revision sessions a week to make sure I was getting where I knew I could be, and my teachers had nothing but praise at parent's evening; they told me and my parent's that I could comfortably get B's because I was putting in the work and my most recent class test had a score double the previous. That's what made the CAGs so surprising.
While mocks aren't all encompassing, there are students who got said grades in mocks and had better CAGs.
After getting our grades, we eventually got a letter telling us that senior staff had moderated our grades. i.e. If they didn't like them and found there wasn't much 'evidence', which my head of year had said about my UCAS grades, they went down.
I know my grades have been inconsistent (In two subjects they range from an A* to a U) so I haven't got much basis there but my internal predicted grades in September (before my surgery) were CDD as well. Surely, my recovery means I'd be doing better? And that the previous tests aren't accurate basis? And on this note, it looks like they haven't used my extenuating circumstances at all which apparently could count as maladministration? I just feel like it's unfair because it's not actually a teacher grade anymore, it's adjusted to fit the school's agenda.
Things to note:
Our maths class was approx 6 lessons behind the rest, which meant we generally did worse in papers because we hadn't finished.
I am an external student, which I've found didn't generally do well compared to their internal counterparts at my school.