I have finished the main quest and on 95% completion, but I dont have this trophy yet? Is it a glitch or is there some way I could have missed out on a lesson somehow? If so, is there some sort of lesson guide where I can redo the lessons?

So if I miss this trophy, can I go back on my saved games and reload and get the item I missed or will I need to have all the items? (ie can I have collected all items accross different saved games or does it need to all be on the same game?).