How to get rid of a lisp?

Please talk to your mum again about speech therapy, it is supposed to help you anyway, as you are seemingly uncomfortable with your lisp and are willing to do some work in order to get rid of it. There is nothing embarring in having articulation therapy, and besides, the therapist can only give you some exercises to do at home and you may not even need to have longer speech therapy sessions! Speech therapists are fully trained with how to deal with these kind of things anyway, so they will be able to find out what causes the lisp.