When you're unsure about something and want to express your doubt, "wonder whether" isn't the only option. You can use "question" or "doubt" to convey similar meanings. "Ponder" suggests a deeper, more contemplative uncertainty. "Mull over" and "consider" imply a more deliberate thought process. "Speculate" and "conjecture" tend to suggest a more open-ended, hypothetical wonder. "Hesitate" suggests a reluctance to take action without first knowing more. Finally, you can use "second-guess" to express doubt or skepticism about decisions that have already been made. Experiment with these alternatives to "wonder whether" to add more nuance and variety to your writing.