I have worked at a call center and I understand the feeling. Everyday I felt mental exhausted and emotional drained focusing on my stuttering during calls. After 8 months I left when I got hired at a better paying job and felt a lot better. Don’t quit you have made it a year and a half that is a big accomplishment just start throwing out applications everywhere you would be comfortable working. It’ll feel worse being jobless and being anxious about trying to pay your bills.