Sorry kissme - I didn't read your post properly! 
I meant 1.6 carbs per portion of stock then on top of that the added vegetables. I'm not great at guessing carb amounts but guess with the veg it comes in at about 20g carbs for the soup.
You should be fine with this, but:
a) it's probably worth weighing your veg next time you make this, to work out the amount of carbs, just so you know
b) whether it's low or not depends on what else you're eating in the day
c) try substituting shallots for the onions, as this will lower the carbs further
My breakfast would usually be 2 sticks of celery spread lightly with peanut butter, handful of almonds or walnuts and a small tub of natural yogurt.
This sounds good, but just we aware that the carbs in peanut butter can be high - check the back of the jar. And also, when you say 'a handful' - how many is that?! A handful can be quite a lot! Again, check the back of the packet. And again - cracked record emoticon! - check the carbs in your yoghurt, as this varies quite a lot between brands - but especially, make sure it's a full fat yoghurt, not a low fat one.
Sometimes breakfast is a few slices of cheese, few nuts and maybe 2 Ryvitas and about once a week I would have a small bowl of porridge made with water. I tend not to eat lunch but might have a few nuts sometimes.
Ryvitas are not low carbs, and nor is porridge. However, this may not matter too much if you're maintaining - it all depends on how many carbs you can tolerate - but I'd try not to have these too often if possible.
Dinners are the soup I described home made or a veg stir fry with cauli rice, or a green salad with tomatoes, red onions and cheese or egg. Sometimes I make quorn mince bolognaise with courgette 'spaghetti', or a Quorn burger with onion wrapped in lettuce leaves with grilled tomatoe and quorn bacon
All this sounds good too - although check the carb counts of the Quorn.
Overall, this is probably OK - but only you will know! If you start to gain, then have a look at the things I've highlighted.
However, my other concern, looking at what you've described, is what seems like a relative lack of protein and possibly fat. It's important that you eat good fats and quality protein - can you introduce more eggs, for breakfast perhaps?