Can you elaborate more on the routine you did for 6 months? Did you keep increasing the jelqing and stretching times? How was your EQ throughout the 6 months? Did you warmup prior to the exercises? This information might help tailor responses.
Stretching is probably the best exercise for length with the lowest time requirement. But if you stretched for 6 months and gained nothing then I suppose there’s ADS/Extender work, but those are at least 4 hours a day or hanging, which also requires a significant investment in time and consistency for results…
As another question…why did you keep going for 6 months of the newbie routine if you didn’t gain anything?