Did they give you two different needles for your PIO shots? They gave me larger needles to draw the shot up, then I'd switch it out to a different one. It was still a big needle but was smaller than what I drew it up with and the needle hadn't been dulled out. What I learned in nursing school is always switch out your needles when giving IM shots. It will go in easier. I have a heart shaped barley bag that I'd heat in the microwave and use so if you have something like that it'd be good. That thing has been with me for a long time. I used it going on 4 years ago for all my IVF cycles and use it very routinely for headaches or just when I'm cold.
Good luck tomorrow. Remember if they are worried about hyperstimulation drink lots of fluids, esp. ones high in sodium like gatorade. Update us when you feel up to it!
I'm so excited for you!!!!! Good luck today!