I also had a strange pattern of weight loss which followed a similar pattern to yours...
1 week above average weight loss (I'm a lady so 5lbs is above average)
1 week below average weight loss (something like 1.5 - 2lbs)
When your losses are not consistent it is easy to get caught up in the emotional rollercoaster of disappointment and elation. My best advice is that in the long run only you know if you are doing anything different on the lower weightloss weeks. If you genuinely are doing nothing different (I know I wasn't) then for your own sanity it is better to accept the pattern that your body has settled into and try not to react emotionally to the number on the scale.
Afterall, the number on the scale is only part of the picture, there are your body measurements to take into consideration, your general wellbeing (I felt great on the programme) and also you will soon start to notice a change in your fitness levels and stamina.
I know in the early stages you rely heavily on the number on the scale to reassure you that the programme is working. On the weeks where your inital reaction is disappointment, ask your LLC to do measurements - you may find that the inch loss fairy has been to visit instead!
Take care and chin up
Every day that passes you are closer to your goal
Love Laura