Not the answer to your question.
Please don't be mad, but I would suggest you don't waste any additional time on that.
It has started flowering. With such a dwarf even a reveg would be much slower and probably not healthy at all compared to a fresh start. Edit: seems like an autoflower from an unknown breeder, so no reveg probably.
Regarding your question, if you put it in it needs to measure, of course it's changing. Anyway, get yourself some ph stripes and measure input and drain. Cheap electronic devices can measure wrong, calibration issues, and so on.
Mixing your own soil is awesome, but if you have issues perhaps just stick with a commercial product.
Anyway just start over, even if you love this little one.