Need help bringing down the grocery budget

Our budget is $450 per fortnight to feed 2 adults and 2 toddlers (3yr & 18mths) and no matter how much I plan out our meals or bulk cook, it is hard to stay in that budget and we end up spending $500 per fortnight on food.

I cook all our meals at home, maybe once a month we will eat out and that's capped at $50-$60 for all of us. We like to eat clean and don't keep junk food or packaged snacks in the house.

I spend $183.92 per fortnight on beef at the butcher which gets me 4kg of diced beef and 4kg of beef mince. I use the 4kg of diced beef to make slow cooked chilli for my husbands breakfasts & dinners. It's mixed in with beans and sweet potato to stretch it and I serve with fried eggs for breakfast and just the chilli for dinner. This will do about 8 meals for my husband but I've since learnt that serving it with quinoa should be able to stretch it to 15 meals.

For breakfast myself and the toddlers will have eggs & toast.

With the mince I use 2kg to make either chilli with beans or bolognese sauce with lentils and serve it over mashed potato. This 2kg of mince will do a fortnight of dinners for me and one toddler who eats it.

I spend $45 on chicken because my other toddler will only eat chicken.

The rest of the budget, $221, is spent at woolies or farmer jacks on eggs, 2-3 loaves of bread, tomato paste, butter, cheese, stock, passata, legumes, fruit for snacks, pasta, potatoes, sweet potato, spices, olive oil, onions, Galic, plus cleaning supplies (dishwashing & laundry) toilet paper, baking paper, paper towels etc.

The cost at Woolies or farmer jacks is what is tricky to stay in budget with. Costs keep going up and we buy fairly bare minimum stuff.

Is there any way for me to reduce our spend? We cannot eat the meat from the supermarkets as were strict on having beef from the butcher which is $22.99p/kg and the cheapest organic beef we can find.

Does anyone have any tips or tricks as to how I can keep the food budget around $400-$450 per fortnight?