Hi There,
DO you have a friend or family that could do it for you ? I remember when I first start B12 shots I couldn't do it either at first. I would take it to my parents and my dad would do it. I am a nurse and it was still hard for me. Keep on trying , you will get over this until then get some help. You also could go to your G>P and get the nurse to do it there.
Good Luck,
Janet