Hello there,
Questions like these are very difficult to answer. Usually in case of exams, students are a bit overwhelmed. They are not very rational when evaluating their own performance. It's easy to feel you did worse or better than you actually did. It's not a fair evaluation on our part and one should avoid thinking too much about it. It puts an unfair pressure on you. The marking is usually fair, and if you feel like it isn't in any subject, you can opt for re-evaluation. Don't worry too much. Good luck.