Cant find the last bunker

Im kinda confused rn. I found all bunkers (except the last, of course. The puffton luxury bunker or smth like that and i saw like 2 or 3 cutscenes with Timmy. Im not sure what i should do now. I have the ancient armor and pretty must every item you need in order to progress (except the artifacts, i have only 3. Are they necessary to finish the game? Im sorry to ask but i trying to avoid internet guides to dont have spoilers. I just dont know what to do now)