I am sure it will be a whole different day in 10-15. :-)
It sounds like you were in the groove.
Generally, the difference in sail trim, between 6-8 and 10-15, is that, at the higher wind speeds, you'll want to trim the jib even a bit flatter. That means a bit more tension on the jib sheet. It also means that, when you raise the jib, you should slightly increase the halyard tension. In strong winds, you will need a winch handle to help you trim the sails as tight as they need to be.
Also, whenever you flatten the jib, you should think as well about flattening the mainsail, because it is also probably becoming overpowered. The mainsail can be flattened by increasing the tension on the halyard or cunningham, and by increasing the tension on the outhaul. There are also other devices that can be used to shape the sails, but you can learn how to use them after you have learned the basics.
It helps to keep the big picture in mind. In all but light winds, the genoa and mainsail are capable of producing more power than the boat can use efficiently. Your objective is to maximize their power in lighter winds, and to progressively reduce their power in stronger winds. You increase their power by making their shape more full, and you reduce their power by making them flatter and by reducing their size.
Finally, keep in mind that the sails don't operate independently of each other. You always want to balance the amount of power generated by the jib against the amount of power generated by the main sail. If you depower one, you should generally depower the other. If you don't, and have too much power being generated by one or the other, then the boat will tend to pull one way or the other, and you will have to use more tiller pressure to hold your course. Whenever you feel tiller pressure, the rudder is acting like a brake, slowing the boat. By balancing the pressures between the main sail and jib, you can reduce that tiller pressure to a minimum.