Some quick comments here, hopefully useful in your case:

1. she is right with regards to you controlling negative emotions. They will still be present but silent , awaiting to be unleashed. Unless you use better strategies to master them before they create unnecessary damages in your life

2. That thing going on with your mum, might be , and i'm not being 100% sure here, that there is an anchor , with regards to a negative emotion, that has been created between you two. It seems easy for a simple comment to escalate into an argument.

If you dont find any positive result with the psy, try an anger management specialist. If you cant find none in your area , let me know and i'll try to help