Sorry, if I had a really good idea, I would have run it up the pole already, so what follows may be of limited use...
I still like
Citizen as a good career descriptor, but it arguably belongs to the background group, if one is making such a distinction.
Roles like
Journalist or
Athlete are ideas that CT never really emphasized from a PC perspective. There are a number of potential careers that imply locality, or being tied to a specific place or market, and therefore aren't ideal for traveling PCs. That's very much a TU flavor issue, but from a 'traditional' CT-style view of adventuring, these make better patrons than PCs.
Your current 'adventuring' career list covers the general spectrum of traditional CT roles pretty well. I think the key to rounding out your list should be in your skill list, versus the careers you have in place. Are there any awkward inclusions or exclusions? Can a player get decent access to all the skills available, and does the skill packaging in the careers make sense?
The scope and granularity of the skill list can dictate how the careers get split. For example, I think breaking
Doctor out of
Scientist makes some degree of sense, especially since there is a traditional role for medical skills as a starship crew position. However, if your only doctor-specific skills are First Aid and Medical (and there's nothing wrong with that, per se), then that's pretty slim pickins to develop an entire career around.
I like to think about the small ship crew positions first, since that's kind of the basis of the free trader aspect of the game. Where is your Steward skill? In
Official, probably, which isn't horrible by any means.
Scientist covers medical, and between
Explorer,
Navy,
Spacer, and
Tech, all of the other crew slots are well-covered. That actually works pretty well, I think. No obvious weakness that I see.
You might look at
Official. It's a pretty useful abstraction, but it may also be trying to rope in too many skills in one place. Just as an exercize, if you haven't already, go ahead and map out some careers you're unsure of; a twelfth career may emerge heuristically once you start finding wrinkles in your implemention. It's an old programmer's trick to switch from top-down to bottom-up (or vice-versa) design to work out problems.
Bleh, that's not very useful -- sorry!
Although using
Citizen as a twelfth career doesn't seem terribly ingenious to me, I still haven't come up with a better idea in my own thinking. I also like
Colonist as a descriptor. Along with
Barbarian, these three can make a nice set of tech-based backgrounds: pre-industrial, pre-stellar, and stellar, respectively. But that doesn't help you any, LOL!