Katie, I know how frustrating that is! Stay calm and know that if you have to do it again, you can.
Geting everything ready and close at hand. Try putting the strip into the meter part-way so the glucometer doesn't recognize it and start timing (and asking for blood), but it won't fall out. Once you get a good drop of blood, pick up the glucometer with your free hand push it the strip in the rest of the way (I tap gently on a table), then touch the tip to that nice drop. If it shuts off or you get an error code, take a deep breath, pet the kitty and try again.