The reason you have low soil carbon is because you are tilling the soil. The reason you have weeds is because you are tilling the soil. The reason you have poor soil structure and low water infiltration is because you are tilling the soil. All the other things you are doing are great, but pretty insignificant compared to the benefits you would get from stopping tilling. Buy a direct drill and get some sheep or cattle onto your land and you will see huge benefits. Also you need to get much more species diversity into your cover crops. Check out Gabe Browns work in North Dakota and Colin Seis in Australia.