Hi Gemma
 
A friend of mine has been a WW always, lost her weight from kids etc no prob but recently gained a stone.  She had been similar to you, lose a pound, gain half - although she did say she thinks it would shift quicker if she was 100%.  She has now swapped to slimming world and she has 7lbs to go.  She lost a pound last week and her weigh in today, will let you know how she gets on.  I think when you are so close, your body doesnt want to part with any more weight easily
 
Good luck though - im sure you will be fine esp as you been 100% xx