Hey Suzanne,
From recollection think we had the same issue with constipation then runny pod with the felini. Ours had very sensitive tummy and being a Birman also fussy so we had a lot of trial and error. He's seven now and I would say we have got it just right in the balance for him.
Well done for persevering, think like us humans, need to find something that is tailor made for both your cats and it could be different.
Also we learnt whilst there was a lot of advice out there on the Internet and I'm sure a lot of it is sound, we had to decide what was best for us and ours even if it meant we might not have got it down to exact science when it comes to everything raw, but he's going great on what we are feeding him on and for us, the nature menu nuggets have been a huge help.. Purr fect though might not be perfect
I'll find you the link cos a month or so ago I looked, couldn't find their UK link but I think I have Nicole's email who was the reputable seller of the mix. Not sure with Brexit whether this will impact?
I've just taken the initiative to contact Nathalie in Canada to ask if there is a store for UK any more, I remember it was Talzenden or something like that, would you like me to let you know the response when I hear?