I haven't read this whole thread but keep in mind the development may be a bit delayed because the temp will be a bit low. At least that was the case with others who have hatched in the bra. It would be better if you started the bra thing half way through but this egg will get a slow start at the outset. Even if the egg was at your exact body temperature, it would still be a degree low. Being external to your body, it might be 2 degrees or more on the low end.
Have you put a thermometer in your bra to see what it measures?