I have done some research, and think I may have to stick with the Stevia for now. Apparently a lot of powdered 'Low Carb' sweeteners add things like maltodextrin for bulk. When you look at the nutritional value, it often lists carbohydrate per 100g as almost 100. It may be that small quantities won't have much effect on my blood sugars, but if I can work out the right quantity of Stevia to use that will probably be best.
When I say my meringue was a disaster, perhaps I should elaborate. I was looking at a recipe that listed 3 egg whites and 175g of caster sugar. I tried hand whisking the eggs and adding a small amount of Stevia. After a while whisking, the mixture was not firming up. I thought to myself that it must be the lack of sugar, so I added a heap of Stevia. After a lot longer whisking, it still had not worked. My arm was hurting from whisking, and I thought what the hell, I'll put it in the oven and see what happens. Half an hour later, i had four small objects. They looked nothing like meringue, but did look a bit like Yorkshire puddings. As they looked edible, I decided to try one. You may not be surprised to hear that it was packed pretty much with pure concentrated Stevia. It took ten minutes, a large dollop of mayonnaise (All I had to hand) and all the water in England before I could stop retching. This is the part where you can all laugh at me, because I was a genuine idiot. However, I have now learned the dangers of going to the kitchen without due respect for your ingredients!