Another possible venue is *gasp* fan fiction. You don't get paid, but you will get feedback. Most people tell me a first novel rarely gets published.
Certainly my first novel, as originally written, even with what little I know now (and I freely admit, I don't know much), I wouldn't expect to get it published. I'm on my third re-write of it and think it's getting better with each re-write. I still believe in the story because everyone who has looked likes the concept. I just need to keep working on touching it up.
Oh, and like you, I was inspired by another series (Star Trek in my case) but I set the story in my own universe and deliberately changed certain things (for instance, I have a light drive which travels through wormholes instead of warp drive).
I also realized when I started working on it that I could imagine a different world than the classic Enterprise (though I realized after some people read it that I never described the bridge of my ship because I always pictured the Enterprise. I finally redid the design of the bridge in the third re-write, making it different from the Enterprise. This is a danger when you write a story inspired by someone else's work -- even if it's your original world, you end up borrowing an awful lot and have to make sure you aren't in essence writing someone else's characters -- for instance, I had to make a conscious effort not to write the first officer of my ship as Mr. Spock with a different name.).
In essence, the story is the question of what's life like on the ships that aren't the "pride of the fleet" combined with a coming of age story (it's MG fiction).
Anyway, best of luck with it.
If you honestly believe in your story and you feel it's good, a fourth option (besides the
"dump it and move on", "give it a shot, what the hell" or "fan fiction" route) is to polish it to a glow, make it the best you can possibly make it, then, once you're really happy, put it aside, write something else, get published, get a name and then try to pitch the story as a published author.
Oh, and my apologies in advance if I've rambled too much about my own work. I find I do it sometimes, but I hope I had something helpful to offer.
Eric