They should have mostly hay, 85/90% of their diet should be hay.
They should then have one cup measure of veg per pig per day and one tablespoon of pellets per pig per day.
Also, you shouldn’t feed cabbage daily as it can cause bloat. If you do give them cabbage it should only be a small amount. 5-6 leaves of cabbage and lettuce is too much. .Lettuce doesn’t contain many nutrients and is mostly water - one leaf a day would be enough.
On a daily basis my piggies get: fresh hay which I top up four times a day. Two tablespoons of pellets (one tablespoon each). For veg, they then get a half an inch of cucumber, a few sprigs of coriander, a few slices of bell pepper. I then rotate in some other veggies such as one green bean, one baby corn, an inch strip of spring greens, other herbs such as dill, a thin slice of courgette (if they will eat it which often they don’t!), a small piece of celery
There are some fantastic guides on here which show a sample daily veg serving. I can’t link it, but you will find it in the long term diet thread if you search for that,