Not sure if this is really the problem in your situation but there has been some glitches with companions that show them wanting to speak with you then when you get to the ship the conversation never happens. Also a lot of companions conversations are based on affection and/or part of your class story etc.. I myself played an Assassin and Ashara is lightside but i manage to max out her affection and "romance" her so I would dare say Vette is the same way. Hope this helps and just keep doing things that gain affection with her and see how it goes