By using hand towels and small sized bath towels when you have children you are still able to change them often but don’t have as many loads to do because you can fit more of them into the machine. After a shower or bath you can hang all the wet towels (not dirty ones!) on the line in the sun and save yourself washing when you don’t really need to.
I use about 1 teaspoon of eco laundry liquid (much less than recommended on bottle) per load (and cold water) and washing always comes out clean. For really stubborn stains or icky things that need to be sanitized use Sard wonder soap (one bar has lasted me about 4 years) rubbed directly onto stain and soak in a bucket of warm/hot water for a couple of hours before tipping into machine for a normal cold wash.
Sunlight has an amazing sanitizing effect on towels and bedding and is much cheaper than using the dryer or hot water for the whole wash. Wait until machine is full to do a load (unless you have half a load and know it is about to rain for a week!)