Sometimes injection pain is depending on grade of test .
Human grade seems to be pain free compared to some UGL .

I rotate glutes and quads myself .

I also find 500iu/week hcg does the trick for me . ( 47 and trt patient here )
I would stick to 250iu 2x/week and increase if you feel needed.
The atrophy takes a few weeks so your not going to wake up 1 day without your jewels .

Others can comment on AI .