You don't have a major flaw. But you certainly have landed in a job with some excellent people around you. It sounds like they care about you, and want to see you continue to succeed. The real question is "Do you want to work at improving your fluency?" When you have went to speech therapy in the past, did you work towards fluency, or did you just go through the motions? No offense intended. I have both "went through the motions" and later worked towards fluency. Putting in the work made all the difference for me.