Its not a question about doing everything wrong. Its a matter of learning as much as you can and then making informed decisions.
We weren't born with knowledge, we acquire it so don't beat yourself up.
I'm not saying you or anyone is wrong, I'm simply saying it's not the norm so you need to question and observe and make adjustments for your individual case.
Have confidence in yourself. Some things you simply cannot prevent but you can try to control them.
I think anyone who takes the time to ask a question is a real hero! It takes guts to say, "I'm not sure" or "This doesn't look right". Especially in a public forum where you are exposed to criticism.
Believe me, if we didn't care, we wouldn't respond to anyone's questions with our own experience or knowledge.
BUT don't take everything you read or hear as gospel. Do consider every point made. If it fits or sounds logical, try to verify it with another credible source like your breeder or vet. You will get many differing opinions so you have to make the ultimate decision. Not all breeder, vets or owners are experts so remember, you don't have to follow anyone's advice but do listen.
If you ask a question of enough people, you will begin to see a concensus, a general similarity in answers. Those answers are the ones that we most likely believe and that's probably OK. I would tend to be swayed by the majority myself but I also remind myself that 25 or 30 years ago, we all "knew" that saccarin, the sugar substitute, was perfectly safe and that vitamin E had absolutely no value as an additive.
Well guess what! Things changed. Now we are told that saccarin is a carcinogen and vitamin E is good for us.
We originally thought that elevated feeding dishes would prevent bloat. Now we are told they cause bloat. Both theories come from reliable sources, scientists. You can see how it's easy to become confused and feel like you are doing everything wrong.
All you can do is search for the truth in as many places as possible, stay open minded, be prepared to adapt and radically change your ideas and make decisions based on what makes sense to you.
There's a term for this...they call it "life".