Where do you think the inaccuracies are? Are you missing any significant contributors like gas, fuel oil?
In the UK, the CO2 to generate electricity varies throughout the day due to high levels of wind generation. Last 24h in my region, y-axis is g/kWh:
If you can find similar data for wherever you are, and if you can track power consumption, you could work out an instant and cumulative CO2 contribution from your electricity.
I do the mean of the day, what’s why I said that this is not very accurate. For the other CO2 sources, I use bike and public transport all the day and no gaz in the house. But you’re right, I should have add them if I use them.