Question regarding fallout 3 ending

Hello!

I'm still playing fallout 3 right now and I think I finished the finding my father quest after freeing him from Braun's simulation world and now going to begin the Waters of life quest.

My question is will this be the last quest as far as the main quests are concerend?

I know there are multiple endings but will finishing this quest trigger an ending?

I think there are a few more main quests, The ending happens when you go to the jefferson memorial for the second time. Also note that you cannot play side quests after finishing the main quest so go ahead and do some side missions.adrake4183

There is a mod that will allow you to continue to play after the main quest is complete.

Link to mod