Hi ya Fiona,
The weight loss LC journey has been 12 weeks; if you look ~ my profile, you'll see that I've got a lot to lose. Weight loss ease/difficulty is so often relative to our starting point.
Comparing yourself & your weight loss to others is so self destructive, DON'T DO IT! I sure wish I could say that I was only 30 lbs from goal
However I'll be there one day (she says with hope).
About depression; I recently read the Heller's CAD book. It sounds like losing weight, improved insulin function etc will help with low serotonin levels. I sure hope so because I'd like to eventually get off the meds I use. I'm one of those truly chemical depressives. Miss one dose accidentally & I'm a weepy mess
Of course it is many hours later before I realize why the weepies have struck. The med I'm on is a serotonin re-uptake inhibitor; it works by keeping serotonin in the blood longer. They don't make one high like the Valium of old.
Have you looked into SAD (Seasonal Affective Disorder) the lack of sunlight basically makes one depressed. Check out the several posts in the Fibromyalgia/Chronic Fatigue/S.A.D. forum.
Doreen & Rachel in particular share about their experiences.
Since you are located in the UK, S.A.D. could be a possibility
Wishing you a great day, hope the sun shows up