Thing is there is no direct answer at this point in time. It just says we're sent beyond the reach of time "Until now" there is no mention of how many years. Now going by looks isn't the best way to go either. Some people have the look of aging quicker than others example. IRL I'm a 31 years old but I look like I'm at best in my early to mid 20's (some people even go so far as to jokingly say I look like I'm 12) When I'm with my YOUNGER brother I get carded for alcohol beverages while he doesn't (Even when my grey hair isn't colored). So I'd say wait it out by the time a Realm Reborn starts up we'll know how many years have past since Dalamud fell and collided with the world.