That was me at 18. Stuttering isn’t caused by nervousness or anxiety. It does exacerbate it, but it isn’t the cause. As for everything else, reach out to someone, an online stuttering group, a speech therapist, someone who you can talk about this and learn some strategies and techniques to manage the symptoms. As for me, I've had my stutter for 50 years, joined military, attended university, graduated with a masters degree in Industrial/Organizational Psychology, married, had a child, and for my career I am a National Trainer for a major medical center........all with a stutter. Do not let it hold you back. It is very frustrating, agitating, irritating, but I know what I want to say and I will say it, whether it takes me a minute or an hour.