Re: 6th kyu forever
I trained for nine years without taking a single test. When I returned from the US in 1975, I had the rank of first kyu, but Kanai Sensei gave me the rank without an examination. Back in the UK, I trained in a local dojo and my university club, but my instructor wanted some assistants to cover for him when he taught seminars elsewhere, so I took my first ever grading test, for shodan in 1978.
I had just one hour to prepare, but I passed and this stood me in good stead when I came to live here. The Japanese regard shodan as the point at which serious learning really starts and so I think you should consider shodan as a long-term goal.
On the other hand, I have a student here who has never taken a test. He trains regularly, as does his son, who has just started taking his kyu tests. His son is a teenager, but has the aim of taking his shodan when he is old enough. (I think you need to be sixteen.)