You've gotten some excellent advice so far and I have some thoughts to share and points to clarify.
If you mentioned the birds' ages, I missed it.
Are your birds laying yet? If so, how is the production? What is their age and how many eggs are you getting on average from the 30 layers?
I'm not really surprised by what you are reporting.
Reds (bulk of your flock) need lots more feed than leghorns which were bred for highest egg output per feed input.
To do a little research and take a set feed weight that is reported chickens need and only provide that, when clearly they need more isn't doing yourself any favors.
Chickens are voracious eaters. They need fresh complete feed available all waking hours.
If feed isn't available, they'll eat whatever they can get in their mouths. That could be bedding, feces, etc. Which would you rather they eat? Feed will contribute to health and production, most other things will detract from those.
They eat primarily to satisfy energy needs but also to get the essential amino acids they need.
By limiting feed and supplementing with vegetables, fruits and sprouted grains, you are cutting their protein intake.
Let's do a little math. 8 pounds of feed (16% protein) and 6 pounds of wheat/barley sprouts (max 10% protein) comes out to 13%. First of all, that is too low for body maintenance and production. Secondly it isn't just about the crude protein percentage.
Animals require an array of amino acids for the synthesis of tissue, regulatory, protective and secretory systems every day for health and production.
The latter foodstuffs (sprouts) are woefully deficient in lysine, methionine and tryptophan.
So your statement that "So overall, it was easily twice what I've read that they "need"" is incorrect because you are only talking about pounds provided, not the nutrition therein.
Most of my birds free range over an area with a variety of forage and this time of year there are lots of bugs, frogs and greenery. They eat half the feed in summer than they do in winter.
If you're unhappy with the amount of feed they're consuming now, you'll hate it come winter.
There's no cheaper way to feed chickens for production while providing optimal nutrition than to keep a complete feed available. There are many illnesses that can develop from birds not fully fed.
Your challenge is to limit waste. The type of feeder you use will help. A feeder with fins around the rim will prevent billing out.
Putting some type of catch container under the feeder will catch what they throw out and you can reuse it.
Keeping the feed under the building at night while the chickens are locked up above is an opportunity for feeding rodents and wild birds. You could be losing lots of feed that way. Feed should be put away at night where rodents can't have access to it.
Another way to limit waste is to ferment feed. That will bind up the fines where the micronutrients and synthetic amino acids are and prevent billing out.
With 30 birds, that is easily doable. I've made fermented feed for as many as 70 birds.
It is a little more of a hassle than bulk dry feed but I sometimes cut as much as 1/3 of feed consumption by fermenting.
Keeping chickens is expensive. You won't have a money machine with 30 hens.
Egg farms make money due to economy of scale. They have tens of thousands of birds and buy feed by the ton.
If you could arrange to buy in bulk, you would save money over buying in 40 and 50 lb. bags. With 30 birds, that may not be feasible to keep feed fresh.
There aren't berries on the berry bushes now are there?
I close off the berry patches during flowering and fruiting but let the chickens run in there the rest of the year.
