ahh this happened to me last year...
i originally has 4A*s 4As 2Bs. before you say, wtf those are good results, I know they are. however, I also know I could have done a LOT better, in particular in the englishes. i was predicted A*s for both, I was on target for this grade in both, and i came out with an A and a B. I was sooo upset on results day, particularly because of lit, as i had put so much into that exam (one i revised most for) and come out with a B. i eventually got it remarked as it was 2 UMS off an A. it went up 7 UMS (wooooo!) so i now have 4A*s 5As and 1B.
nearly a year on, i look at my gcses and think they're actually pretty good. yeah, i could have got A*s in maths and science, but i dont really care. A levels are way more important, and by this time next year the only thought you will give to GCSEs is how you wish you were doing them again rather than AS levels. OP you might be disappointed on results day, but then again you might not (I know someone who predicted themselves 14 Bs/Cs after doing their exams and came out with 8A*s and 6As) Just remember it wont be the end of the world, and enjoy your summer. dont speculate about what you might have got - you'll only make yourself feel worse.