Sounds like you might have some air in the system. Did you use the
bleeder screw to let air out as you filled it?

If it's been losing coolant without any noticeable leaks, it might be
spitting out of the overflow bottle as you drive. This could be from an
ill-fitting rad cap (if it doesn't hold the coolant at the correct
pressure, it lowers the boiling point which in turn forces coolant out
as it vaporizes), get a new OEM cap at your Honda dealer, about $15-20.
If this doesn't work, it could be a leaking head gasket, either
allowing combustion gasses to enter the cooling system or allowing
coolant to leak elsewhere in the engine.

I know the coolant temp sensor doesn't work correctly when it's not
submerged in fluid, so this might be sending false readings, telling
the computer the cars still cold.