Hi Debbie,
Most people do fine on Synthroid alone for the first few years after RAI and eventually need to add T3. Some people do fine on glandular extracts and others do well on synthetic formulations.
TED typically develops either within a year after RAI or around 6-10 years after RAI. The replacement hormone doesn't play much of a role although becoming hypothyroid can trigger TED.
Since TSI is a type of TRAB, your antibody results, if done with the same lab draw, would be considered erratic, meaning that one or both results are flawed. Your doctor should have asked to have the tests repeated. Since you mention TED, it's likely that TSI rose and TRAb as well. LDN typically lowers antibody levels but if you reacted to one of the fillers this would account for a rise in your levels.
In general, it's best to use the type of replacement hormone you tolerate best at a dose that keeps FT4 and FT3 at least at mid-range. Best, Elaine