I'm afraid I agree with what so many others have basically said: she's milking you for another Bible study and another hour or so of field service time. In effect, she's using you to make her report card look better at the end of the month. JWs are very opportunistic, which is a shame, really. But it's true of many of them.
I would tell her--politely, if she'll let you--that you really meant what you said when you told her that you don't want to continue the study. Which is what she's tricking you into doing. But tell her you'd still like to be friends and you'd still like the mags.
Let's see if she's still your friend after that. Odds are, she'll stop coming. At least for a while. If she runs out of Bible studies in the future, she might come back to see if you'd like to restart the study.
If she doesn't let it go at this, you'll have to be more forceful.
BTW, many here have a very different opinion of the literature than you seem to have. Which is fine. But that's why you're getting all these reactions. Maybe you should try fact checking the articles some time. I think you'll begin to see why we're raising our eyebrows at you if you do.