I get mine from ADS. They text me before it’s time to send them and they send them out promptly on the date. They have been great. But sometimes you don’t have a choice of who you get them from.
Running short because of something happening is a good reason to restart your sensors so you can build a back up supply in case something goes wrong. Something will go wrong with a sensor at some point and you will need a replacement. If it’s at the end of your supply you could also run out. Dexcom is sort of slow in sending replacements and sometimes they like to tag it onto your next shipment from your supplier. I included a link that tells you how. A guitar pick works really good to snap out the transmitter.