What country are you in? Not all products can be found on Amazon in every country.

A few important things to keep in mind is that we need to buy shampoo for our scalp type and conditioner for our hair length. It might sounds trivial, but many people buy shampoo hoping that it will also treat their problems with the hair lenght, which is not always the case. Also, as we grow older we tend to lose more hair than before. As far as I know, one of the few products available over the counter that can improve hair density and hair fallout is Minoxidil (Rogaine/Regaine is exactly the same thing, but it's more expensive for reasons).

Look into products for the "curly girl method". Despite the name, they are suitable for any hair type. Generally speaking, this method preaches being more mindful of the ingredients in the products we use and what they actually do. It promotes a gentle approach to hair care. Many conditioners are specially formulated to allow easier detaning and brushing.

Www.isitcg.com can help you figure out what the ingredients in products do to your hair. Just copy/paste the list of ingredients and you'll have a breakdown with useful ingo.

If you noticed dandruff apearing and such, then perhaps you'll want to start with a clarifying shampoo and a scalp exfoliator. A clarifying shampoo is great at cleaning the scalp and removing build-up (many shampoos and conditioners contain a lot of non-water soluble silicones that will build-up over time and/or harsh alcohols that are meant to provide a quick solution for oiliness but can be too drying for both scalp and hair.)

Some clarifying shampoos are gentle enough that can be used every day, like Suave clarifying shampoo in USA or Palmer's Cocoa Shampoo for dry damaged and coloured hair . Since you have highlights, you will want to choose a shampoo that has gentle cleaning agents and so is specifically targeted for coloured hair.

A line of great shampoos and conditioners that can also be used as masks, and is definitely easy to find on Amazon is the "Ultimate Blends Hair Food" line from Fructis Garnier .Products in this line have good ingredients and there are several to choose from, deoending on your need. I personally like the Aloe Vera the most for my hair, it gives me moisture. The conditioner/mask tub is pretty big too and it lasts for a bit.

A tool you might want to look into is using a brush with soft silicone teeth to lather your scalp with shampoo, like this one. It's like a mini-massage and my scalp feels squeaky clean.

Another tool that I found useful was a wet detangling brush, like this one or this style. These brushes have soft nylon or silicone pins so it's easier to detangle, as the hair glides better. What you do is you put a lot of conditioner through your hair lenght, then use the brush to evenly distribute the product through the hair, so that every strand is covered in the goodness, starting from the ends and then going up and up as you detangle, all the while trying to pull as little as possible. After that, you leave on the conditioner as usual for a few minutes and wash it off when you're done.

If any of this makes you have more questions, please feel free to let me know.