@virtuenow my only question was how do shampoo just the scalp and not get the rest of the hair soapy? I will try it out soon. Thanks for the tip.
I had the same problem for years as a natural. I tried everything out there and almost gave up. Then I finally found some products that penetrated my hair and allowed it to hold moisture. I use Aubrey Organics GPB for deep conditioning. Its a restructuring conditioner that helps to rebuild your strands and balance out your protein and moisture. The effects last about a week, so using regularly once a week has compeletely changed my strands around. And by the way, balancing your protein and moisture is the best way to address your porosity issues. There is no quick fix!
Also, I use castor oil rinses; and spritzes w/castor oil http://www.longhaircareforum.com/showthread.php?t=150965. It is very similar to glycerin in what its supposed to do (enhance moisturize) and how it feels, except glycerin dries my hair out. Have you found glycerin to be helpful to your hair at all? I know it works on alot of people, but not all. It may be time to ditch that product...
The last thing, I found shampoos to be very drying to my already dry hair. With that, I only shampoo my scalp now w/diluted shampoo in a color applicator bottle. (2-3 squirts shampoo, fill rest of bottle w/water). The rest of my hair gets cleaned by my Deep conditioner, Aubrey Organics, as a DC-co-wash!
Iron deficiency -anaemia can cause hair to grow dry and brittle. I would get some blood work done to check, or just start taking a supplement with iron in it. There are other threads about this if you do a search.
Also hard water, calcium and mineral build up can cause the hair to be brittle, dull and extremely dry which doesn't respond to any product. Chelating shampoos are good and shower filters. All the best x
Don't let it get you down if the gpb doesn't give amazing results right away. And the advice you've been given here is excellent. I tried gpb and I liked it (probably the smell & that its a natural product) but it only gave minimal good results for me at first. Just like some others joico, etc. Now I keep aubrey gpb and hsr in my stash, along with joico and amla oil and such. Find out if heat works for you. And exercise mow the yard or something with that conditioner in to get those cuticles open, until you can get a steamer. Idk use a sit under dryer, heating cap, or (carefully) a pot of boiling hot water with a towel over your head to trap steam. Heat dcing has changed my hair as far as getting those cuticles open. And yes, definitely try to keep your hair stretched it will help in covering every strand with whatever you're applying, moisturizing, dcing, etc.