Undecided questions
Are the words "gonna", "wanna" and "gotta" used in just the US?

They're used in other countries, but they still make you sound as if you failed school.

I have a Filipina friend who lives in the Philippines (Luzon) and in casual conversation she uses these informal words. I think it is cute to hear them and if used in proper conversation they are handy. I have a college degree and never failed a class or test in my entire life and I use these in conversation with friends!

In my english teacher opinion is The words from american english so american people used that but we can use the words although the words is not formal for many people especially british and the meaning same with "want"

Yup! They're used in Canada as well ;)
Gonna = Going to
Example: I'm gonna do my homework eventually!
Usually used in an informal conversation.

Wanna = Want to
Example: I wanna go to the mall today~
Again, informal usage with this word

Gotta = Got to
Example: I gotta go to the bathroom!!!


Usually these aren't used in proper English writing... They're used mostly in text messages. These words are spelled how they are said : )