Fallout 4 - Where are the quests

Solution 1:

Looks like you finished the main story line. What Maxson refers to is the quests given by paladin Danse's team. You could try to add mods to your game to track down the quests that you are missing or change the gameplay.

If you finished all the quests, you may want to fix some objectives for yourself like chasing all the unique monsters and deathclaws, gathering power armors, exploring vaults, building huge settlements or trying new perks.

Last but not least, you should consider exploring the sea bottom and the irradiated area in the south.

If this is not enough, all that's left to do is to buy a DLC