All of those 'seen' parasites are in your digestive tract. If you don't zap, they just eat a hole and crawl right out of your digestive tract, so if you still have 'big' worms, you've no one to blame but yourself.
You won't see worm parts from outside the digestive tract for the 7 millionth time. Duh. But that's the worms that get killed by zapping, so if that's the only proof you'll accept then you really wouldn't know zapping worked. So how did YOU zap??
And sheesh--all that puttzing around. I'm glad I used the zapper right. You don't sound very well from your 'method'. If in fact you're even sick at all.