Actually at 2 months and in this weather they will need at least a kilo a day each, plus veggies, its not cost effective not to feed really well whilst they are this young, once they get to 4 months cut back to 2 kilos a day, plus veggies in winter, as weather improves feed a ratio of 4 parts vegetable replaces one part nuts, but always give a minimum of a kilo a day, bulking the food with as much veg, fruit, nuts and even a little bread. If they have plenty of room to run around like Kate, you will get well grown meaty pigs with a decent but not excessive amount of fat.
To conclude at this weight, having not long left mum and in this cold weather, providing they have access to outside feed them really well. If they appear to be a bit too fat, cut back a little. Its more a case of feeding by eye than the book. Its like children, some get more exercise, some eat masses and never put on weight, etc.
Its all a learning curve, a lot depends on where they are if its freezing, windy, etc. and on the protein level of the feedstuff. Dont worry, they will thrive.
HOpe the weather is better with you, we are dragging around bidons full of hot water 4 times a day just to allow them to drink, have doubled the feed intake and doubled the straw in their arcs (which they still eat).