So it is with a Game Master. The fact is, nothing you create is "real." The world and the adventures you put the PC’s through are just illusions you cast on the players. The only way to maintain that illusion is to not do anything to break it. And one of the easiest ways you can break the illusion is to have out of character ("OOC") discussions about what didn’t happen.
For example, let's say your players have entered a dungeon, and they have a choice between a door on the left and a door on the right. Let's say they enter the right door, fight a monster, take its treasure, and then leave the dungeon, without ever going through the left door. Avoid the temptation to have that OOC discussion telling your players what was behind the left door. If the player characters do not open that door, they should never find out what was there.
This requires a certain amount of discipline, but I think it's worth it. The players will feel your world is more "real" if there are certain things there they are not allowed to know about. Keep in mind that in our own real world, there is far more which your typical person doesn't know about, then there is that they do know about. This not knowing is what makes our world seem so big and mysterious, and so it will be with your imaginary world.
Also, keep in mind that material not revealed in a dungeon can always be reused in another dungeon. If you reveal parts of the dungeon that were unexplored, you no longer have the option of using it later. However, do not reveal to the players that you are doing this either, it will ruin the illusion if they know that parts of dungeons are "moving around" to new dungeons. Even if this is true, you should not discuss it with your players.
You may be asking, "But what about things I put on Scabard, isn't that revealing things the player shouldn't know?" My response is, I never put on Scabard things that a character wouldn't know as general knowledge from living in that world. For example, the biographical information of a king, or a powerful wizard, might be general knowledge known to most who live in that world. If I do put information generally unknown on Scabard, I put it on a secret page, or in the secret section of a public page.
And it's never too late to start; however, if your players are accustomed to having after game OOC discussions about your world, you will have to explain to your players that you are no longer going to reveal things they didn't see. For example, you will not answer the question, "What would Lord Hawley have done if we had stolen his magic sword?" The answer is, "You did not do that, so you don't know." And then, say no more.