Hi Nicola,
I'm terrible for eating and my PTs and current trainers every time I mention being 'stuck' ask if I am eating enough. Can you note down your food diary for yesterday and today to have a nosey at? It is true if you don't eat enough your body won't shift ... it's a constant battle depending on your diet or food preference. I too have gone from SW to going it my way.
My last stone and half was a NIGHTMARE to move and when I gained that back on through a move I am back to NIGHTMARE mode. Do you exercise?
... and of course welcome to Social Slimmers