Talk to your Armouries Support Centre/Orderly Room before the Christmas stand-down, they should be open during the week - call from work or school. They should be giving you a detailed pay record in any event - check with your unit, they may have gotten them late from the pay people. It's a piece of paper with all the days you worked listed. KEEP TRACK AT HOME OF ALL THE DAYS YOU WORK and make sure you check them off against the report. Pay sheets go missing, and no one is going to track this stuff for you! You'll be surprised at how often a half day here or there might get missed.
Good luck.