I'm sure you know there's no substitute for book learning. It complements experIENtial learning (or learning from experience), and experiential learning complements book learning. They're really both needed to make inroads into having a healthy beautiful lawn that your neighbors will admire, and not shake their heads at [chuckle]. I loved your story :-)

How many grubs per square foot do you see? They're not a problem unless they reach 6 grubs or more per square foot.

Beneficial Nematodes would be an organic method to control grubs. Carbaryl compounds sold as name brands like Sevin, can be a non-organic, synthetic, chemical means. I'd try to learn as much as possible about both methods before choosing to go organic or artificial. I've been lucky enough to never have a grub prolem, so I'll pass the baton off to others, especially those who may have actually fought grubs on their lawn, and can tell us firsthand what they think of the organic or synthetic method they tried. Synthetic chemicals can take a severe toll on your grass and soil organisms, so you gotta be really careful with them. "Doctor we cured the disease, but the patient is dead."

You also wanna be really sure what the problem is: grubs and not something else.

You may want to consider hiring a professional. Some of them really know their stuff and produce good results.

Yes you can fix this but, because it is all weeds, it will require a full renovation. Start with a power rake or slit seeder to chop out all the vegetation. Rake or blow that into your compost pile. Then scatter seed, roll the seed down, and start watering 3x per day, 5-15 minutes each time, every day, for 2-3 weeks depending on what seed you planted. The idea would be to only moisten the seeds at the surface. Do not drench the soil. Fescue would be 2 weeks and Kentucky bluegrass would be 3 weeks. After you have about 80% germination, start to back off on watering frequency and go a little longer duration. Eventually you want to be applying 1 inch all at one time. By the time you get there, it will be cool enough that you should only be watering monthly. Mow when the grass is tall enough to mow - about 4 -5 inches. Mow toward the high side. I like it all the way up, but others like it more in the middle. Fertilize with starter when you start. Fertilize again with a winterizer about Thanksgiving. In the spring, wait until May to fertilize. It will be tempting to push that up earlier, because you'll see a lot of advertising. Close your eyes and wait.

If you want to apply a preemergent weed control, do that after the soil temp reaches 50 degrees F and immediately after the spring rains. If you see forsythia blooming, you need to do it immediately. Resist applying fertilizer.

Never use weed n feed products. Fertilize with fertilizer and kill weeds with herbicides. They don't mix.

Six grubs per square foot comes from David Mellor's book The Lawn Bible:

He writes "If there is an average of six or more grubs per square foot present, it's time for a treatment."