Hi!
First of all, if you're really concerned, I think it would definitely be worth letting your teachers/school know you were unwell and getting a doctors note (if possible). That way, when teachers are writing your references, they can say what you were targeted and why you may have achieved lower.
In terms of how it will affect your university applications, it completely depends on what you're applying for, the required grades and your personal statement. I achieved B, C, D, D, D at AS (C, D, D in my subjects I carried on to A2) and at the time I didn't disclose any of the medical issues I'd had during exams. I explained to my teachers in September and begged and begged for my grades to be raised, as I knew I needed at least A, B, B for Computer Science at York (my dream degree). I was told that I would probably get 5 rejections due to my low grades in relation to the asking grades of where I was applying, but I managed to get 4 offers from universities asking for A, A, B to B, B, C. However, I believe a number of things made this possible. I had a good personal statement that listed programming experience that most applicants hadn't, I'd listed that I was resitting things, had glowing references from my teachers explaining my mitigating circumstances and I was a girl in a subject which normally has a ratio of 1 girl to every 10/15 boys. Despite all of this, I probably got offers by the skin of my teeth and it's common for universities to give offers slightly below the requirements (but normally the likes of one grade down, not 6!). However, the pressure of going from C, D, D to A, B, B and my increasing mental health difficulties got too much for me and I ended up just doing a few resits that year and returning for another A2 year.
You're still in AS and next year is a whole other year. If you do really badly (and you could still do better than you think!), you have a whole 12 months to turn it around and prepare. Resits may still be available and, from what I've read, only the likes of Medicine degrees or highly ranked universities (e.g. Oxbridge) hold this slightly against you.
Discuss your options with your teachers in September and utilise their help as much as possible. I hope you're feeling better and good luck on results day. No matter what you get, it's not the end of the world - my predicted grades this year were A, A, B, without begging! Improving is possible.