Well, as a speech language pathologist and stutterer, that explanation is a first for me. While emotional or psychological trauma can cause stuttering in rare circumstances, it usually happens suddenly after a severe traumatic event. I'm pretty confident in saying that having a mother with a temperament that changes a lot is not why you stutter. There is no research to back that claim up. I'm not sure where you live and what access you have to other speech therapy providers, but I would recommend someone who specializes in stuttering if you can find one. The vast majority of people who stutter started stuttering early in childhood as part of a developmental difference between those who do not stutter. It is due to neural differences in the brain regions responsible for speech production.