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Not all my English language teachers are native speaker, but they told me that "never use I'm FirstName LastName when you introduce yourself",
instead they told me that when trying to introduce yourself to new people, I may say "Hi, my name is FirstName LastName, you can call me Kitty..."
I wonder under What circumstance I can say "I am ..." ?
Is it informal and incorrect for one to say "I am FirstName LastName" in a face-to-face meeting ?
if, when I meet with my favourite pop singer in the street, I will probably say to her / him "I am FirstName LastName. I am a big fan of yours"

Edited:
I remembered that they had also told me not to say ""I am nickName" when telling someone else who you are on the phone.

Not all my English language teachers are native speaker, but they told me that "never use I'm FirstName LastName when you introduce yourself".

Instead they told me that when trying to introduce yourself to new people, I may say "Hi, my name is FirstName LastName, you can call me Kitty..."

I wonder under What circumstance I can say "I am ..." ?

Is it informal and incorrect for one to say "I am FirstName LastName" in a face-to-face meeting ?

If, when I meet with my favourite pop singer in the street, I will probably say to her / him "I am FirstName LastName. I am a big fan of yours"

Edited:
I remembered that they had also told me not to say "I am nickName" when telling someone else who you are on the phone.

Not all my English language teachers are native speaker, but they told me that "never use I'm FirstName LastName when you introduce yourself",
instead they told me that when trying to introduce yourself to new people, I may say "Hi, my name is FirstName LastName, you can call me Kitty..."
I wonder under What circumstance I can say "I am ..." ?
Is it informal and incorrect for one to say "I am FirstName LastName" in a face-to-face meeting ?

Edited:
I remembered that they had also told me not to say ""I am nickName" when telling someone else who you are on the phone.

Not all my English language teachers are native speaker, but they told me that "never use I'm FirstName LastName when you introduce yourself",
instead they told me that when trying to introduce yourself to new people, I may say "Hi, my name is FirstName LastName, you can call me Kitty..."
I wonder under What circumstance I can say "I am ..." ?
Is it informal and incorrect for one to say "I am FirstName LastName" in a face-to-face meeting ?
if, when I meet with my favourite pop singer in the street, I will probably say to her / him "I am FirstName LastName. I am a big fan of yours"

Edited:
I remembered that they had also told me not to say ""I am nickName" when telling someone else who you are on the phone.