To those who (apparently) misunderstand the question: I’m fairly sure she means to say “a native speaker of English from the USA”. Júlia, what you said is perfectly understandable in context, but be aware that “native American” is a phrase used only to talk about the people who lived in the Western Hemisphere before the Europeans arrived.
You should go to the language partners page https://www.italki.com/partners and input your criteria: English, native speaker, learning Portuguese, female.
As far as preferring a girl, anyone who has used the internet before can guess that Júlia’s inbox is already full of messages from males who think every site on the web is for hitting on ladies.
Bem vinda, Júlia, e boa sorte.