We as stutters have some limitations even though we have potential to achieve more . I believe it’s accepting who we are and forgetting bad memories keeps us moving . If you are feeling down just take a break and focus on something else like on a hobby . It’s very normal to feel lot of pressure to give presentations and even for normal speaker they are tough . Just talk to your professor and see if there are some alternatives on giving presentations. May be to a small group . It might be a valid reason to quit college . Quitting college just because of presentations will be a stupid decision if you think about this after 5 years .