Hi Nikki,
I don't have a clue how slimming world works? But if its anything like weight watchers, write down everything you eat and have to stick to it. Exercise, drinking water, keep away from rubbish, sorry!!!
I found that i think i was eating too much zero point soup and salads so i've cut them out, would have them for lunch normally.
Also last week i was watching secret eaters on channel 4 and i realised that i eat my childrens left overs at dinner time especially potatoes so i cut that out this week, it all adds up..
At least you aren't up? Start in earnest again today. One bad day or week isn't the end and don't let it be either just start again and stick with it, slow and steady is the way to go..