Dead space 3 save doesn't show up

[tharyummystuff]

So I owned the disc version of dead space 3 and I played it through a couple times, but recently I lost the disc so I bought the version off of the play station store and installed it but when I go into the game none of my saves show up, my only option is to start a new one. Is there a way to fix this or do I have to start over?