Hi Elodie,
Try to post your offer in the Jobs in Reunion Island section, under the babysitting category, it will be more efficient.
If you don't mind me asking, are you looking for a native english speaker, please ?
If yes, maybe once you're set up, you could reach out for students by putting a notice in students' home/residencies. If no, i think you will have no problem in finding once there.
All the best,
Bhavna