。
I'm afraid I might be a burden to you.
Literal
I [topic-は] you [to-に] trouble become [wonder-んじゃないかな].
厄介になる ('to become a burden/nuisance'). ~んじゃないかな ('I wonder if it might be that...') combines explanatory んだ + じゃないか (negative question seeking confirmation) + な (wondering). A layered hedge expressing worry about imposing.