Somebody please help me

I'm so worried rn. Guys I'm in my third year at college I had to resit my AS because something happened in my family. I study chemistry, biology and psychology. I'm doing my exams rn and even though I have revised so much for chemistry I panicked in my exams and I think I messed them
Up. I'm so upset rn bc I put everything aside and revamped for chemistry but I don't think I did well in the exams even though I knew everything. I don't know why I'm like this honestly this is a horrible feeling as I tried so hard. I have a offer at a university AAB however at this rate I don't even think I'll pass chemistry never mind get a B. I've had 3 out of my 4 exams
For chemistry and think I've messed them up. I really want to get into a good university doing a good course. Please somebody help me

You can retake next year... But this depends on your grade obviously, when you get your results and see that you haven't done well enough, just enter as a private candidate and study at home for a retake...this would mean studying A levels for 4 years for you right? You might be hesitant because of this but if it's going to get you to a good uni and a course then retakes are always beneficial.

I don't actually mind taking a gap year tbh but I don't think good unis will
Even look at my application as 4 years for A levels is kind of ridiculous don't you think ?