Woman I need a regimen!!! What, precisely, are you using and how? Give me deets!!
Also, you may very well be heat-damaged from flat ironing your hair. Not necessarily, but if you've done it consistently then more than likely you have some damage that will eventually just need to be cut off. That can affect the hair's porosity. I've read from other naturals that heat damage can lower the hair's porosity, and for a lot of low porosity ladies, shea butter is the debil. DEBIL I say! (sorry, I'm a little loopy right now) I've heard that it just sits on the hair and doesn't really moisturize.
If you haven't already, take a look at the 4a forum. A lot of women there have experience with some of the issues you've raised. FYI, I'm a 4a natural.