Sadly, as you said there was deleted images saved in some obscure part of the internal memory of my phone. The police view that was that as an engineering grad I was fully aware of how devices store images.
The context, nature and intent of the image is important. Yes there was no nakedness involved- I would equal it to a bikini shot, you could see exactly the same as what you would see at a beach.
Because the image was sent within context of a flirtatious conversation, the image is indecent. The key here is the context in which the image was sent/recieved.
I understand why people are trying to tell me to fight it, and I've had legal advice, where its been advised that i plead guilty to avoid a lengthy sex offender registration. If I please out, I will likely get 2 years and a permanent criminal record. If I argue that i didn't recieve it, i would be looking at five.