"I have to use the bathroom right now!"
Translation:Ninahitaji kujisaidia sasa hivi!
No, -ji- is the affix for the reflexive pronoun, i.e. referring back to the subject of the sentence. It is always -ji- independent on the subject pronoun. Compare these:
jikata kidole: I have cut my finger (litt. I have cut myself the finger).
kukata kidole: I have cut your finger.
nikata kidole: You have cut my finger.
jikata kidole: You have cut your finger.