Why does my bread always turn out heavy like scones rather than nice and fluffy and light?

I used a self raising flour recipe with 7g yeast, a cup of warm water, a little salt, a little er. Mixed it together, kneaded it for ten mins and left it for 30 mins to rise to twice it's size. Then put it in the oven for 30 mins approx. It went nice and crispy on the outside and tastes nice, but it's a little heavy and doughy in the middle like a scone.