You have an unusual history of hbvdna, alt, and treatment. I don't know why your doctor stop and start your ETV/TDF treatment. It is also very unusual to have HBV induced fibrosis progression from F1 to F4 within two years, especially when you reported your hbvdna was always low. To get a better picture, you must provide your ALT at the time you test for your hbvdna and when you have your Fibroscan. Also at one time, you were on ursocol, why?
In general, to have such rapid progression of fibrosis while hbvdna is low, you and your doctor must try to find a cause, other than HBV. Possibilities are:
1. Fatty liver disease;
3. Co-infection with HCV, Hepatitis E or Hepatitis D;
4. Other liver diseases.
Once you get an exact picture of your health condition, you can receive appropriate treatment(s), and you will get better. No need to worry and losing sleep.