Boost your current laundry detergent by adding some vinegar and baking soda.
I don't use laundry soap that has dies and perfumes in it. I use Armand Hammer - unscented. I use less than what they specify in the instructions and I boost it with vinegar and baking soda. You don't need a lot - about 1/2 cup of vinegar to 1/4 cup on baking soda. This seems to keep the whites white and clean the protein out of towels and underwear as well.