Personally I do not see any benefit of O level on matric.
O level is hard for student, very costly, high fee & you read the books which do not belong to you. If you believe in yourself that you’ll continue it further i.e. A LEVEL, then do it. But it has been seen that many people come in Matric or intermediate afterwards.
We made it a status symbol. It is easy to bring good grades in Matric system as compared to O level.
You must sit in the test. Pray to Allah he will guide to the right path.