Progress Monitoring

hello PP friends,

hope everybody will fine, ok! my question is that i am facing a situation where i use to compile a progress report every week where i use to measure the progress from the pour dates, but the problem is that the project manager is not consistant on his words and pushing me to change the target pour dates and creat futher delays, so the progress report become useless as the pour dates are keep changing and the programme looks like out of control.on other hand i started using concrete voulumes for measuring the progress but because the project is quite huge and the changes are quite frequent so its almost taking a lot of time of me measuring the concrete as QS never bother it measuring it so frequently, so the concrete measures of the base line programme no longer realistic any more. its really a confusing situation for me as if i measure the progress from the pour dates its no longer useful as the pour dates change so frequently and if i go for the concrete volumes it changes with the same pace.
so any suggestions or tips from my Planning planet friends who might have faced the same situation in the past or i might going on a wrong path.

thanks

Tariq