Many use 10,000iu hCG vials lasting 80 days, no problem. Must use BA water, 0.9% benzyl alcohol, not sterile or simple saline.
I have been using #29 syringes with hCG and T for 10 years and never felt that needles were dull. Backfilling wastes T and is an opportunity for contamination. Backfilling advice seems so bro-science.