In support of OP, a portion of fruit or veg for a child is by a rule of thumb, approx the size of their fist, so I don't think she is off on her portion sizes.
I had no limit on budget and I discovered I was malnurishing my children due to many factors, first the calories children need, they need a lot compared to size, I never limited food but because of my misunderstanding on portion sizes and high fibre foods, I was filling them up but not giving them the energy to grow and they where missing vital trace elements.
I also believed that sugar was evil, so no Buscuits, cake sweets, chocolate, small children actually need some empty calories...as they need them for energy, not a lot but a bit.
I had twins they where 95th and 75 percentile for height but 4th and 25 for weight until I heard a radio 4 program on child nutrition, I felt sick but fortunately had a tame dietitian at work who went through their diet with me.
They are still at 9, 95 and 75 for height but 50 and 25 for weight, they have more energy ... Unfortunately lol.
Against OP when are you buying? 2008? 95p for milk? £1 for 2 loaves, I shop in Aldi tis brilliant but I can't buy for that price.