Sorry, when I read "I’m losing so many potential opportunities coz of this stupid stutter." I thought you meant that you didn't get the job because of the stutter. Preparing for an interview is normal ofc, but with a stutter it turns into a trap. Still, it seems you powered through to the end, and gained important experience. Now you know that you can do it, despite the stutter! Look at it more positively, remind yourself of this success next time to boost your confidence. With enough success, your thoughts won't be able to tell you that you can't do it.