The image at 1:9 will develop within 15 secs and black within 20 secs literally if you miss with the tounges or drop it back in the Dev, its ruined.
Then you are giving it too much exposure. You don't want to be judging development then pulling it out of the developer at a critical moment. You should give it as much exposure as it needs to develop to completion in the developer.
i.e. you keep it in there until it appears to be not getting any darker.