@OutbackQueen
I really sympathise, it’s awful finding a design you love and ending up with a tattoo fail that looks nothing like it.
I think you'd be better off going for a straightforward cover-up rather than trying to redesign it. The current tattoo’s angle, shape, and overall "smudginess" would be hard to correct, and I doubt you’d get close to your inspiration picture.
The ammonite looks great though, and it’s cool it fits the theme of your other tattoos.
For what it’s worth, my second (and last) tattoo was also badly messed up despite personal recommendations and checking the artist’s portfolio. It looked nothing like my design sketch—more like I’d had it done in prison with a Bic biro and a sewing needle.
To make it worse, it was on the nape of my neck, so many artists wouldn’t cover it. The guy who eventually did told me he usually avoided neck work, but when he saw it he sucked his teeth and said, “Ach, who did that to you, hen?” He agreed to rework it and was fantastic at explaining what he could and couldn’t do. In the end, it turned out lovely—something I could actually live with.
I hope you get a good end result and that would come back and show us all it in its new glory.