You've been getting the error of:
"Sorry! There is already an attachment with the same filename as the one you tried to upload. Please rename the file and try again."
It's a quirk of the system to allow us to show attachments in an efficient way as we can.
So before attaching an image, rename the file to something that is unique. So, for example, you could start all your attachments with "Nell1707" so the attachment ffs1.jpg would become Nell1707ffs1.jpg (ort something like that). Or you could just put in today's date 160412 at the beginning, or anything like that really.
All the best,
Trystan