That is a really great drawing ofcourse since I'm a shinRan as well
I shall admitt i really like it, Ran looks perfectly fine in my opinion, but Shinichi's head is a bit too "rounded" and yeah, a bit skinny.
Do not get me wrong my friend,I'm not tryin to be mean or offensive, but I believe honest opinions are one of the best keys to a better art. Not that your drawin is bad or anything, infact its really cool, I myself cant draw like that just re draw Shinichi, the rst is great.