I never carry less than 10 ats. Messes up the 30 day return but that's better than being without. I know I'd be straight back on the hots if I ran out of working kit.
Feel for ya - I'd bag a generic pen or mini from pillbox if it was me (with carts/liquid). I did that when I started because I couldn't wait for the brand stuff to arrive. He's quick!
Emp