I've been a professional SE for 18 years. Even though the job is typically associated with introverted, anti-social people, there is a lot of verbal communication I need to do in order to do my job. Meetings with my team where we talk about solutions to problems, meetings with colleagues around the organization for various reasons, etc. The best advice I can give you is that you need to be proactive in being fluent -- it won't just happen. Stick with therapy and do the practice and exercises the therapist suggests. Additionally, anything you can do to lessen anxiety will help you with fluency.