Turbo training needs to be more structured, with variety of intervals, using a HRM and, if cash permits, a wattage measuring trainer.
Find a, preferably, local coach who can test/arrange a test to find your max HR and other factors. He can then set up a proper series of turbo programmes for you. these are more controllable than road training (tho' you still need to get a reasonable number of road miles in).
The best training for riding is still riding, so you might want to sqap some of your other exercise sessions for time on the bike