RE: "portfolio review" Usually, people have just posted one image or series as a new topic on the forum, and ask for critiques & advice (I see you've figured that out & posted one already!).
For help with portfolios, there are a couple classes you might want to check out:
How to Perfect Your Children's Book Portfolio, Will Terry
Portfolio and Self Promotion, James Yang
(I haven't taken these yet!)
As for a portfolio review by the Pros, I think they have offered portfolio reviews as a live class before, but I'm not sure. You could send an email to: email@example.com to ask if they have anything like that coming up.