Hi
Your cat is a gourmet diner, one day she has caviar the next day she wants foie gras the next truffles and on it goes. I am afraid to say it but she is spoilt.
Pouches and other premium food includinig dry foods contain vitamins, minerals, and other essentials eg taurine. They are actually better for her as they are more balanced than the treats she is existing on.
You need to get into a routine with the food, and don't always comply with her demands.
If you feel she is ill and is really not eating then she needs to see a vet, otherwise if there is only one food down provided it has not gone "off" then she will eat it eventually.
Get some really good quality dry food Royal Canin, Hills, Burns, James Wellbeloved etc. and leave it down for her so that she has always that option and start leaving the wet food until she eats it.
Treats like tuna and chicken and prawns do not need to be given every day.
HTH