It's normal to feel concerned or scared. But since you say you did everything by the book then you would realize what is happening is that you didn't get everything out on your first flush. (No one does). Do the next series of flushes at 2 week intervals and not 4 weeks. Or even do the next one in a day or so. It takes at least 20 flushes for people to completely clear everything out, and this is the ideal situation when you aren't making new stones due to metabolic problems.
Stay away from alcohol, fried foods, white Sugar and anything else that impairs liver function while you are preparing for the next flush. Probably the next 1-3 flushes you will start getting the bigger stones out.