I think its a really difficult decision to make but I would suggest telling your mum hun. Maybe talk through with her too about your worries that she will look too hard and see things that arent there, and that you dont want to be constantly watched. But, like youve said, she may pick up on things that you dont notice, and quicker than your SW would.
And, if you dont tell her hun, is it something that will make you more stressed? Having to try to hide it from her??