@Sonia99
You've been given wrong advice by all commentators on this thread. The study permits, post-graduate work permits require disclosure of any criminal arrests, charges or convictions. Having charges dismissed in court or being found not guilty does not relieve you from the obligation to disclose it. Having clear police certificates or being told not to mention it by anyone also does not relieve you from the obligation to disclose it. It was challenged in federal court several times and it was ruled time and again that being innocent as in your case is not a defense for the failure to disclose. So having filed those previous applications without properly declaring the criminal charge you did fall into misrepresentation unfortunately despite being approved, it could be that local police and provincial courts did not upload your data into CPIC for it to be visible to IRCC. When it's time for you to apply for permanent residence, if you plan to, a more thorough background check will be conducted by the RCMP.
I am sorry but this is how things work in Canada. It is one of the few countries in the world that require disclosure of non-conviction records but the only one that deems it a material misrepresentation for failing to do so, because it doesn't matter whether this could have affected your application you only had to block a line of inquiry when the officer was assessing your application.
So, for your current situation your lawyer's advice was correct in sending in a web-form about your situation to IRCC, and this is especially true if you intend to stay or live in Canada in the future. Having declared your case to IRCC before being found out will be considered by them and usually it does fix the problem if the applicant was already admissible on the true facts. I have seen a similar case to you where a British person voluntarily declared a juvenile case before renewing his work permit and it was accepted by IRCC.
Keep in mind that IRCC can still choose to file an inadmissibility report against you, meaning that you will be asked to go back to your country. This is a matter of discretion so no one can provide you with an answer on what could happen. Remember that this is not about the earring but rather about misrepresenting yourself on your past visa applications, which is taken to be more serious.