Hello.
Outside of your values, your situation was much the same as mine.
I leave you this link in case you want to take a look:
From my experience, which is based on experimenting and testing, with some reading about training (I clarify that I am very far from professional coaches) I have found that what really makes you fast is training in Z2. You don’t need hard stimulation all the time, once a week is fine.
Not all people feel good about the same training and I say this because for some reason you didn’t continue with TrainerRoad (just like me ). I realized that it is not necessary to suffer training to improve. In fact, I reached my peak of form (4.33 W/Kg coincidentally the number you want ) with Coach Jack, which I never could with TR.
I can only tell you that you must try, stick to the plan, be patient and measure your progress. If you notice that it is too soft for you, you can modify the intensity, the advantage of CJ is that it is very dynamic and adaptable.
Good luck and keep us updated on your progress.