I just punched in your extracts/honey and see that BeerSmith 2.0 does give an OG of 1.063/64. Here are my thoughts on what could have happened:
1. incorrect measurements on sugars added
2. incorrect reading of refract/hydrometer
3. incorrect reading of final volume (should be easy to tell based on how full the ferm is).
So if you KNOW you have close to 5 gallons volume, then it's got to be issue 1 or 2 above.
If you are CERTAIN you added those amounts of sugars, then that only leaves issue 2.
Are you certain you took your original gravity reading AFTER adding the top-up water post-boil, and are you confident that nothing affected the accuracy of that measurement?