Month to a month and a half in between the flushes to my opinion are too long brakes for first flushes.
My body, for example, manages to produce new stones in this period of time, and when the old ones are still there, it sometimes gets more complicated. You should flush every two weeks until your first stone free flush and then switch to the maintenance mode (once every two or three month, or whenever you feel like).
It seems to me that stones that remained in your system have rolled further to the exit or have changed their position and that made it a little more difficult for you.
It happened to me once, I had to reflush a week after, and the result you can check in the Image Gallery
It would be great for you to flush again in a week, but if your present state bothers you too much, flush now. I am pretty sure you will get some big stones out.
You may consider parasite