Hello and welcome to the forum. I understand your problem, having had the same issue with two of my dogs. Coincidentally, I too had a short spell of feeding Canagan when it was very new. It is a good product. Sadly, despite me giving considerably less than the recommended daily allowance, my dogs put weight on too and it took a long time to get it off.
Weight control can usually be achieved by reducing the quantity of food (calories) and increasing exercise. This means dog food only (accurately weighed) and no table scraps or extras. However, as you have found out the former is problematical when you have a hungry dog.
As you already know, you are giving two very good products with with higher protein and fat levels so my advice would be to drop one of them. You don't say which Forthglade product you are using but I would be inclined to stop that for the time being but if you decide to stick with that then drop the kibble. In this way you can monitor the intake more accurately and you will know exactly what you are giving. Fix an amount and stick to it. Weigh the dog weekly and if the weight is not coming off, reduce by 10%.
FWIW my experience of giving a good quality wet food was that the dogs gained weight rapidly, despite giving less than the RDA. I have friends who experienced the same thing. That is why I suggested taking your wet food out of the equation, if only for now. However this does not mean that there is anything wrong with them and they will inevitably suit some dogs. It may be due to the high fat/protein but that is just a personal observation.
Years ago I dieted one of mine using James Wellbeloved Light. Their customer service lady said that dieting dogs need lower fat and higher protein. My experience is that she has a point. It's no good giving high protein/high fat food if you can only give tiny amounts and the dog is consequently always hungry. I have found that it is high fat that seems to pile the pounds on so now I give products with 11-12% dry weight. The protein is in the region of 27% and I top up with chicken or white fish because then they get the protein but without the fat. I've tried all sorts of permutations with food and this seems to work well with mine. However, other people have different experiences and I have read that it is actually carbohydrate that turns to fat on the dog. I realise that the food I give has a higher than average carbohydrate level but the dogs are satisfied because they have something in their stomachs. Like us, dogs need to be sated after a meal. I also give three smaller meals per day.
Please come back to your post if you need further help. Also, we would like to hear how you get on and what steps you decide to take to control your dog's weight.