Pokemon RNG help! (advanced players only please)?

I can soft reset for IVs just fine and have done so a few times but my problem is shiny breeding. I can just never get the pokemon shiny or with the right nature! The ability is always right but....I've used 3 different guides and have retried multiple times to make sure I didn't miscount when tapping the happiness app, but it never works! Am I doing something wrong here?