I would definitely cut down on the carrots, personally I only feed a small amount as an occasional treat due to the sugar content. I have no idea why everywhere says they can be fed daily, they're high in sugar!
Cabbage can give your piggies bloat if fed every day. I would cut down on that a bit too (not related to their weight though, it's just so they don't get bloated in the future), perhaps feed a little less and not quite as often (e.g. a quarter of a leaf per piggy, 2-4 times a week).
Generally about a cupful of veg every day is good, feed maybe two types of veg in the morning and two in the evening. Different veggies you can feed include coriander, dark leafy lettuce such as cos/romaine/sweet gem (
no iceberg), cucumber, spring greens, celery (cut into inch-long slices so they don't choke on the strings), dill, parsley. More piggy veg listed here:
https://www.theguineapigforum.co.uk...veg-and-fruit-list-with-vitamin-c-grading.42/
Kale is great because it's rich in Vitamin C, but may I suggest not feeding it every single day as it is high in calcium? Twice a week is good. Too much calcium contributes to bladder stones. And they only need one Vitamin C-rich veg per day, so on the days you are feeding kale, don't feed pepper. Just a suggestion.
Good luck with your piggies! It sounds like that rescue is not very good, they shouldn't put up overweight piggies for adoption without telling people they are overweight and making sure you know they have to be on a diet. You shouldn't have had to go to the vet in order to find that out. Unless you got them from gumtree or somewhere similar, in which case the previous owner was probably not very knowledgeable about piggies.