I love natural light and candid moments.
I agree about candid shots, and that is definitely one of my main goals, however, I am frankly put off by photographers who claim to be "natural light" photographers. I nearly downgraded my evaluation of your portraits simply because of my extreme prejudice against that term and methodology. (it's in the thread's title)
Is that harsh? Perhaps, but every photographer who proclaims himself a professional should have a working knowledge of light manipulation. Now there's nothing fundamentally wrong with using available light, and in these two shots, you have produced very good shots using "natural light".
Now, put yourself into the future, and your client has limited time in which to wait for the light, but wants you to get going and make the photographs. What then? Are you going to chase your client away to some other photographer simply because you had not put in the time and effort to learn supplemental lighting and modifiers, or the use of reflectors?
Sometimes the light is good, and you showed us that it was o.k. in this session, but sometimes the light is not good, and you have a choice to make; no photograph at all, a photograph in the dark, a photograph with poor flash, or a photograph with good light, whatever the source.
Please accept this critique in the good-humored spirit in which is it offered.