You're correct. This is going to be determined by both your doctor and your test results. Age will play a major role as well. However 2IU RT is commonly prescribed to those qualifying, but even this varies a bit.
The only logical solution to this is to go get checked out. Then you'll know exactly how much is consdered to be 'too much'.
There's a pdf file out there, I found it a couple years ago on google - on a study of a small asian women. They gave her 18 IU for an extended peroid of time because she was a dwarf. In each picture her face was more englarged.