How do you inject when you literally have almost no body fat left to pinch?

Weird problem to have, I know. Started Zepbound at 278 lbs, currently at 171 lbs. Conventional injection sites, abdomen, outer thigh, are running out of real estate. My abdomen especially; I can still pinch skin but it's pretty thin and I've started hitting what feels like muscle a few times (immediate sharp pain, bruising after).

I know upper outer arm is an option but anyone actually self-inject there comfortably? What's your technique?