Re: Mass Effect 3 Destroy ending and shepard lives
It seems you confuse Total Military Strength with Effective Military Strength. If your Galactic Readiness is below 100%, your Effective Military Strength (EMS) is lower than your Total Military Strength. After the Extended Cut, a maximum of 3400 EMS = 6800 Total Military Strength at 50% Galactic Readiness is needed to see every possible ending, which is the standard if you haven't played the Multiplayer or the Datapad.
[edit]I just now saw that you say you have 100% readiness - are you sure about that?