Is this the female form?
Male. Female form is: "Jestem turystką".
It seems to be one of those words, like mężczyzna, that's considered masculine, and takes masculine pronouns, etc, but ends with an a and declines like a feminine noun.
Dlaczego nie "jestem turystem?"
Oh no, wait. Turysta is male, it's an exception. That's why it has an ą in instrumental. Like mężczyzna, too. The female would be 'turystką' as already written here. I'm sorry, already a bit tired. I'll give you the lingot back
Nouns end with an -a ends with an -ą in instrumental, whether it is masc or fem. Other masc nouns like that: artysta, mężczyzna, kolega.
"... And this is my Luggage", said Twoflower to Rincewind (before trying to sell him Inshore Ants).