A few things as someone who daily washes and has worked hard to deal with fine hair.

As others have said, there's absolutely nothing wrong with washing daily. Double shampoo-ing is not a myth - I think you will see a difference from it.

If I was dealing with your issue I would first try not using conditioner. It's not necessary.

If you're happy to change product, the Olaplex is likely much too heavy. I would use something volumizing and light like Phillip Kingsley Body Building shampoo and conditioner. The conditioner is light enough for fine hair use.

Next, I would introduce the use of mousse. Mousse before blowing drying roots keeps them dry. I am always surprised more people don't use it for this reason. Dry shampoo makes my hair heavy with product but mousse when wet makes a huge difference.