@nickers45,
The ending of a Latin verb tells the person, number, tense and mode of the
verb.
Fatigo is first person, singular, present indicative "I worry". When
you look up a verb in a Latin dictionary, you will find it listed in the first
person singular present indicative. That's why many automated translators
give you give you that form. They are just looking up the word in their
dictionary.
Fatigare is the infinitive, "to worry". Why did I use that? Because
sine
which means "let" or "allow" is used with the infinitive.
I would also advise having someone else verify the translation, especially
since it is for a tattoo.