Honestly man, I felt the exact same:
I felt as though I completely misanswered all the questions, but I think you've done just fine ! I would just try and recommend that you try and keep it off your mind and try enjoy your summer, and even if you don't get the grade for English Language, you could be saved because most A-Levels only really look for good grades in English Lit. Honeslty, my best advice is to not overthink it!! I'm sure you did amazing and it's just post-exam doubts creeping into your mind. I still think you can get a 6, and who knows, you may even surprise yourself. May I ask what A-Levels you're looking to study?