PATIKIL Sports Armband Sleeve, XL Size Universal Running Holder Arm Band Waterproof Phone Armband for All Phones Hiking Biking Walking Jogging Gym, Rose Red

You might try a runners arm band - these are on Amazon and are the sleekest ones I found. https://a.co/d/02H7Qr4B Etsy has similar but I don't know if shipping will arrive in time. https://www.etsy.com/listing/508718470/spandex-insulin-pump-arm-band-standard?ref=share_ios_native_control Have you thought about wearing a runners belt under your clothing, if it won't be inconvenient. https://a.co/d/02H7Qr4B