I'm fairly well-informed on this subject- I've had one published science fiction author as a housemate, another as a good friend, and I'm on a first-name basis with multiple editors at Tor.

You will find it very challenging to get direct feedback from any professionals in the industry at this stage, short of relationships like personal friendship. This is because at any given time, there are tens of thousands of unpromising authors making exactly that request.

If this is your first novel, or even your third, don't expect too much. The bar for minimum quality is extremely high, and author skill does not peak at a young age. If you're still early in the process, and you're still enjoying the practice, keep writing your second and third and eighth books while you look around for your first to be published. As a general rule of thumb, if you don't have a novel that's now vaguely embarrassing to you, then you probably aren't good enough yet. Do not put all your eggs in one basket by writing one very long series; try out a variety of settings, and experiment with your craft.

Often, it is heard that writing short stories to build up a reputation first is a good way to break in to the industry. This is false.

Be aware that no matter which route you take, multiple years will pass before your book is accepted. Be aware that when your first book is published, you will not be paid enough to live on.

Rather than chasing publishers immediately, the first thing you need (need) is a good agent. Being accepted by an agent is a kind of 'slush pile lite' challenge- agents usually have their own slush piles and their own interns to read through them, but their overall volume and turnaround time is much more manageable. You're also much more likely to get real feedback from an agent, explaining any potential problems that they see with your work. Another advantage of having multiple novels written is that you can send a particular novel to a particular agent, depending on their stated preferences. These can be quite specialized- gay and lesbian characters in fantasy settings, hard sf alternate history military adventures- depending on the goals of the agent in question, and it helps to maximize the number of niches that you accidentally fall in to by writing a variety of stories. Make sure that you are aware of your chosen agent's reputation, since there are predatory impostors. Once you have this agent, you will be able to bypass the publisher's slush pile entirely, and your chances improve dramatically.