My hair is soso flat, thin and useless?

Whenever I straighten my hair it goes really flat because its really thin. My natural hair is really kinky. I have layers in my hair and I cant backcomb because it falls out after like 2 minutes! its annoying having such fine hair

Without curling it or anything, how can I make it more voluminous but keep it straight?

My hair is soso flat, thin and useless?

After washing your hair, blow dry upside-down. Then seperate 2 sections top-layer of hair from the under-layer and backcomb under-layer. The backcombing has to be done and sprayed with a bit of hair spray to set. Then only flat iron the top layer because the under-layer won't be seen.