@lots33 my two pennyworth!
At around noon I either have berries ( maybe too many) with ff Greek yoghurt and a sprinkle of sliced Brazil nuts. Or three egg cheese and veg omelette with lettuce, cucumber, red pepper, celery
The omelette is perfect low carb food - hopefully you're also making it with plenty of butter, to get your fats up? Equally, the yoghurt is great - but be very careful with the berries and nuts. If you're not losing, this is something I'd look to cut down/out. You haven't said which berries, and again this is something to be aware of. Blueberries are much carbier than raspberries, for eample.
Early evening I have supper with family. Tonight was sausages and I had three, with onions and a pile of greens (broccoli and green beans)
Did you check the carb count of the sausages? They vary hugely!. If you're buying good quality/high meat content ones, the carb counts will be lower, but if you're buying ordinary sausages, they contain a lot of filling, like rusk, which makes them very carby. You could also cut down the carbs by using shallots instead of onions. (Buy the echalion/banana shallots as they're a lot easier to peel)
Yesterday I had aubergine and courgette stew (ratatouille) with mozarella, or salmon and stir fry veg
This sounds perfect but, again, I hope you used plenty of oil to fry the veg in first? Stir fries are often pretty low fat, so once they're cooked a good tip is to dress them with sesame oil.
Often have celery sticks with marmite peanut butter or cream cheese later on
This is OK - just watch the peanut butter as, again, different brands vary hugely in terms of their carb count.
Drinks - no alcohol, prob not enough water. Tea with milk -2 cups a day. One Coke Zero a day. 3/4 galaxy light hot chocolate a day ( made with water, 38 cals a cup. Is this where I am going wrong?
Definitely cut out the Galaxy! It's not about the calories (generally a much lesser issue if you're low carbing), but that will be adding a lot of carbs that you simply don't need.
No other snacks, no junk food, no ham or bacon etc
Great! You shouldn't need to snack anyway on a low carb diet, as one of its benefits is appetite suppression.
Am about 2/3 stone overweight. I am on lots of meds that cause weight gain
Medications can impede weight loss - but obviously you need those! So it's important to stay as focused as you can on the diet you're following. Have you had a look at the Low Carb Bootcamp rules? That might help you - and you're more than welcome to join us on the current chat thread - we're between Bootcamps right now, but the next one is starting very soon, so why don't you join us there? It's a short one, 6 weeks, but the chat threads continue all the time anyway!
Hope this helps.