Will my dreads thicken up?
Sometimes the hair doesn't make dreads as thick as expected when it's backcombed and people wonder if their hair is just too thin for dreads or something. As long as there are enough hairs per square inch on your scalp to make a bundle of hair as big around as a pencil or so you should have plenty of hair density to make dreads.
The dreads will generally phatten up a bit as they mature so you'll gain some thickness/fullness in the first 3/4 months. During tightening the tips draw up towards the roots making the dreads shorter and wider. Because backcombing technique varies, sometimes newly backcombed dreads can start out pretty thin and they don't loose much length during backcombing. These dreads will usually widen the most in the initially tightening.
When the dreads don't get much wider than the bundle of un-dreaded hair during the backcombing it's pretty likely you'll see the thickness you're looking for as they mature.
Also, after they mature and continue to grow, the hair that would normally shed away continues to add to the fullness since it always stays in the dread.