I too think is English. It's the only language I'm fluent in so that much is natural. One interesting thing I've noticed is that when I'm conceptualizing something, I will have an idea in my head, but out of some bizarre habit I will think the words through.

My point is that I already know what I'm going to say in my mind, but there is no reason to actually hear my brain think them. Basically I go through 3 steps in my thought process:

1. Think or conceptualize,

2. recite what I've thought to myself (in my mind, in English of course),

3. process what I've just heard myself think and act on it.

My question is this: why is step 2 necessary? It would be faster just going from conceptualization to processing, wouldn't it? Maybe it's a habit from reading at a young age when I sound the words out in my mind as I read.