When I'm presenting a Project In School...

When I'm presenting a Project In School... Hey, 16 yr male here, Is it my fault if it takes SOOO much longer than anyone else's presentation? I always have that side thought that everyone just wants me to not presentate because their time will be "wasted". But it is a hard situation for the teachers. What if a presentation should maximum be 5 minutes, but I need 30 minutes to say everything I want thanks for the annoyance of my stutter? Every time I do a presentation in class I get like 1/4 through it, but then my teachers stops me and says we should do it later in private. Is this fair?