You look like your hair is very dense like mine. While some people complain their twists look scalpy my scalp is barely visible once my twists dry. I think you should make sure you make clean straight parts with a comb. I agree smaller twists may help because if you make the same size part as a less dense person you are putting like twice as much hair in your twists. I don't like doing flat twists because my hair won't dry well but when I do I dont go ear to ear. I start from a middle or side part. Not so far to travel in trying to keep it smooth.

Ps if you aren't wearing the twists as your style I wouldn't worry how they look.