Its okay don't stress too hard it might seem very bleak now but it does improve overtime. It was the same with me. I actually started stuttering very late as well...around the same age as you in grade 6 or 7 (12-13). Started very, very mild but got worse overtime and got significantly worse in college. I don't know what causes it, perhaps its tied to confidence or anxiety...I tend to be a very anxiety prone person. Could barely talk sometimes because I blocked soo bad. However after graduating and working several jobs I think the stutter has gotten a lot better overtime. I am now entering my late twenties and I would say a more predictable routine, less stress, and just being comfortable with myself means that the stutter has become a lot more manageable. I also took some anti-anxiety medication on and off which helped alot :) Personally I don't stutter too bad talking to people I am comfortable around whether it be family, friends, or coworkers.