That is a fantastic achievement and a reward for your dedication over the last year.
I have a personal opinion that a poorly gallbladder finally gives up its stones when it is strong enough to do so and it is provided with a sufficient dose of the flushing potion to make it contract to the maximum. As we have learned the liver is capable of supplying sufficient bile on its own is response to the flush potion because people without a gallbladder can flush. Sometimes it may be necessary to compensate for this by increasing the dose.
You have been flushing for a year and I would assume adjusting your lifestyle in the way you eat. This has strengthened the gall bladder and the reflex response. You then increased the dose to exercise the gallbladder more.