Washing your hair every 2 days might be too much for your hair. Especially with the texture description once a week or bi-weekly should be sufficient for it to stay clean.
If you have TRUE 4c hair as you say, then you won't be able to define the coils, so your focus will mainly have to be moisture.
You could always do braid/twist/bantu outs or use rods or rollers for sets.
Cover your hair with a satin(make sure it's finely woven satin made from polyester or silk, satin made from cotton will dry the hair out.) scarf at night.
The shampoo and conditioner you use could contribute to drying out your hair if there are ingredients in them that dehydrate, like sodium lauryl sulfate.
Are they free of sulfates, parabens and silicones(the silicones are handy to protect the hair from heat, but might prevent moisture from getting in under regular circumstances) ?
I ask because you haven't mentioned using any additional moisturizers which could mean that the conditioner you are leaving in might not be providing your hair with the moisture it needs. And if that is the case even sealing with an oil won't help, you will need an additional (water based)moisturizer (first ingredient will be water) that does get the job done, or you will have to find a moisturizing conditioner... and once you do, you will notice that sealing with an oil (or oil based moisturizer) will help lock the moisture in.
You will need something that provides moisture first, if your hair is dehydrated by the wrong ingredients and you seal it, you will be locking moisture out and your hair will become dehydrated.
You can do an ingredients check here to see if the products you are currently using have drying ingredients in them: http://www.tightlycurly.com/ingredients
You may also want to deep condition once in a while, maybe once every two weeks or once a week, it will help keep your moisture balance in check.
Edited by Ritle - Aug 30 2013 at 9:12pm