Pictures/ Screenshots disappearing from my texts.

I have memory issues and find it easier to text myself pictures/screenshots of items with pertinent information I’ll need to reference back to instead of trying to search for them in my camera roll.

When I text them to myself, they’ll be in my text and then of course when I need to see what they were, the only thing that shows up is a white blank text (what would have been the pic) but the written text is still visible and the pictures are gone and nowhere to be found, not even in my deleted album. 

Can someone please explain to me what is happening since this is so extremely frustrating because I rely on the info. 

It seems to be random but what is going on that makes this to keep happening?

I’ve attached a screenshot of what I’m talking about. 

please help