I also want to know if the LED lasted all this time.

I don't want to sound harsh but the design is a little crude.
The dynamo does not provide constant current neither constant voltage.
I think that the 6VAC that is written on the dynamo is the RMS value under a certain load with a certain speed.
That means that the voltage across the LED won't be 6V.
But after the full wave bridge (diodes) the DC output will be 6V*(square root of 2).
Even that I said is not correct because the dynamo's voltage output is not sinusoidal.
Only after a certain (high) speed it becomes a sinusoid. In my shimano hub dynamo the output is like that

As for the batteries, I don't think that NiMH batteries like being overcharged.
When the batteries are not full, the electrical energy you put into them, converts into chemical energy. When they are full, the electrical energy you feed them transforms into heat. Overheating is bad.

I must say that I am not 100% sure about the things I said above because it seems that your design works and the LED stayed alive. But I just can't accept it .
You see, I am also designing a circuit for the same purpose but with switching regulators for high efficiency and I am looking at other's circuits to steal some ideas.

I think that you(N4ZOU) made the PVC bike fenders. I tried making them a few days ago! They didn't turn out as nice as yours but they do their job.