Thats actually quite large. Don't listen to anyone who says its small. Because the average size is about 5-6.5" erect. not even kidding you. My bf is also larger than normal (but not that big about 8.5") but you have nothing to worry about. Just be careful when you have sex..Don't rip anyone apart now. :)
if i were u i would cut it off before it gets to long and strangles you when ur sleeping. or maybe u could just get honest about the true size and accept the fact that it will never grow... the choice is up to you.