Do you account for plate tectonics in the global mean sea level trend?
The principal tectonic processes (ridge building, subduction, etc.) responsible for changing the ocean basins are measured in millions of years and are so slow that short-term global satellite records do not consider them. Glacial isostatic adjustment is comparatively a much shorter-term process (although still measured in thousands of years), and it does have a minor effect on ocean basin size. The current effect has been estimated to be -0.3 mm/yr of equivalent sea level rise due to increasing ocean basin size. This effect is corrected in the satellite altimeter global mean sea level time series and contributes 0.3 mm/yr to the estimated global mean sea level. This is considered a small effect since it is less than our estimated error of 0.4 mm/yr.
For further information see the reference "Sea Level Variations over Geologic Time."