Small suggestion here. You currently have a non-rebreather mask with a bag that does not support your breathing. You can take an unscented fresh garbage bag and use that instead of that little thing giving you a hard time.
Tie up the open end tightly. As in air won't leak tight. Now, cut a hole in a corner where you are going to either push the stub of the previous bag or the bag with the bottom cut out. Remove or open the bottom of the bag on your mask and insert what is still attached into the garbage bag. Tape that up really well. Now you have a really big bag to hold your O2! Then you will have the pleasure of plenty of O2 for your next breath waiting for you - not you waiting for it. Not the best rig, but beats out running your O2. Turn on your O2 and grab a few slurps of that caffeine while it gets up to speed. Less than a minute and you are on it. That should get you through until your cluster mask gets there.
Personally, if I can't get the high flow needed, it is a waste of money to use it. Takes a looong time to get relief and the relief is not lasting at all. Like executing a bat turn in the living room and heading back to the office cause it is back not lasting.
When doing your post hit breathing, dial the O2 back to match your breathing. You should be breathing at a normal rate at that time, so you won't likely need 15 or 25lpm.
And no grease or oil or anything on the threads of anything where you are pumping O2. THMH gave you a great primer on that one.
One more item. Try holding a full inhale of O2 for 10-20 seconds. It really does help. Then exhale with that crunch. Works great. As your pain levels drop, you can relax a bit on your breathing technique. By the end, you should be breathing normally.