I've just reached stage six of the lost grove and seem to be dying every 2 minuets
my current part members are
Light(slot 1),Air(slot 2) and Fire (slot 3)
is there anything I've done wrong with the proficiency and affinity choices?
is it the gear that's the problem ?
or do I need to get better pets than my starters and the first pet I grabbed from the broker?
I've kept them in my party because they were my first team and are the highest level pets I have but do I need to buy new ones?

I currently have 100k gold and 936 diamonds saved up is that enough to make any improvements or do I have to save up more?

You may find it easier with a more typical tank/healer/attacker team, but with this team as-is I'd suggest swapping light's profs, either try out 2hp/2int/1agi or 1hp/2int/2agi. A tank healer needs the agility far more than the dexterity. Air and fire are typically all str and dex, but I can understand an hp prof given they're all low-stat pets. Take one of Air's 2 hp profs and put it in strength or dex, though.

Consider upgrading gear (either tier-wise to stoneweave or upgrading VT via blacksmith, relics first. It may take a while for you, since you only have 100k- I suggest if you don't have them, get some good mission pets set up, make sure you have all six mission slots unlocked, and have pets running missions in the background constantly. Mission reward satchels can add up pretty fast)

Thank you for the help:)