It sounds like your ends are not healthy.. but if they are then it is your technique.. or, Also keep in mind its the summer & its heating up, enough humidity makes my hair poof no matter how slick i get it to begin with! & were not gonna talk about beach air.. beach air is the enemy!

I can just recommend my favorite product combo to try.. which is Jane Carter Leave in on damp hair.. then once dried a drop of one n only argan oil on each section (or redken smooth down heat serum) the matrix is nice too..

Now i used to use Infusium23 instead of the JC and Redken Smooth Down instead of the Argan oil with great results, but im more into natural products and avoiding as many cones while i can. But that Jane Carter is good stuff man, its more moisturizing than the infusium!

flat iron, in small one inch sections.. slowly, running the comb over each section before you iron it. Pass over each peice 2x's.. (comb, iron, comb & iron again) that is enough to get it straight but not fry it.. if you go over too many times the heat will actually cause your hair to not lay smooth.
dense, fine & porous curls |

Poo/Cowash| Bobeam, V05 Shea Cashmere
DC| AOGPB, CJ Repair Me, BrownButterBeauty
RinseOut| Mill Creek Keratin Conditioner, Ology Moisturizing Conditioner
Leave In| Curl Rehab, Bee Mine Luscious Balanced Moisturizer, CJ Smoothing Lotion
Moisturize|Oyin Hair Dew, CR Moisture Milk
Gel| Kiss My Face UMG, Trader Joes Aloe Vera, KCCC
Sealants| Aloe Juice, Whipped Shea, Cocoa & Mango Butters, Castor, & my Peanut Oil Blend =)