HO HO HO do i have potential in long distance?

Your only 13 and 3:09 800 by yourself, im guessing, with no practice. First off whoever told you that was not good is an idiot. If you are the one that tricked yourself into believing that that was not good then your wrong. That is a great time, if you practice more and get out running right now about 20 miles a week with the sprint speed you apparently have you could be a serious 800m threat, you never know unless you try.