I also suffer moodiness when my BS is either high or low. Since I started testing I have realised that I can pretty much tell when it is outside my normal range by the way I feel. Dopy, tired, unable to concentrate and irritable means the BS is high, edgy, shaky, irritable and irrational means the BS is low (or originally what my body though was too low and giving me false hypos).
However as we are all different we all suffer different symptoms and as you can see from the lists, some symptoms are very similar, so if possible I would suggest you test when ever you notice you are becoming moody and even if you can't stop for a meal try and keep a low carb snack handy to offset the symptoms until you can stop.
Hope you get back on an even keel soon, having serious mood swings in no fun for the person involved or their family.