Question about single use vials/insulin needles.

Hello! Currently doing Monday/Wednesday/Friday as my days for injection SubQ in my thighs
My doctor said it’s ok to use the same vial for the 3 days then just throw away Friday.
Pharmacy said to only use one time and throw away.
Which is right? If I throw away Monday, my supply wouldn’t last anytime at all.
30/30/30 then I’d be discarding/throwing away 10.

Doctor said it’s ok to take out testosterone with insulin needle(been doing this for months this way).
Pharmacy said not to, because it would take too long to do, and said to do IM instead of SubQ.
Again, who is right?
Thank you again!