Exactly it's not! I studied Optometry at university and I struggled in first year too, I failed a couple of exams because it was so different to what i was used to! But i resat those exams and passed. So even though at the time it felt like it was the end of the world it wasn't because thank God i had the chance to resit and improve. Once I found my feet and asked for the right help I improved massively in second and third year and i graduated and so will you! Also don't compare yourself to others, you're on your own journey and you will succeed.
And I had OSCEs too, So many !! OSCEs are tough especially when you didnt have a chance to sit the mocks. Mocks are sooo important for OSCEs because it helps to calm the nerves for the real thing as you already have an idea so dont be so hard on yourself because its not your fault that you were unwell and didnt get that chance. Also they are practical/clinical exams, which we're not used to from A Levels.. You'll get used to them the more you do and each time you will improve. If you do fail then imagine this as your mock! Hope you're ok. You're going to be absolutely fine, take this from someone who was in a very similar position not so long ago.