I would be willing to bet that if you can look at the screen instead of the keyboard, you will see the mistakes as they crop up, and be able to fix them. I know I don't have proper typing technique (fingers not on the right keys), but I can avoid typos and go pretty fast nevertheless - I just correct the typos as I make them. But maybe you wouldn't notice them? I know you don't always see the typos in your own writing when proof-reading, so maybe this would be similar?