Hi there,
I'm not across the criminal law, particularly in SA, so hopefully someone else on here can give you a more definite answer. However, I did have a look at the criminal record laws in SA and from my reading, it looks as though your conviction may be spent. If this is the case, it wouldn't/ shouldn't show up on a police check anymore. However under the exclusions to spent convictions, some agencies are still able to access the spent convictions. Have a look here:
Criminal records
Also, is there a peak body that you need to register with before practicing as a counsellor? If so, you should look up their admission guidelines and see what it says about applicants with a criminal record for a minor offence.