"Bastard" is closer to "illegitimate" in that regard, and Tera and Harvey were engaged, so I doubt that Fitz's name is a reference to Harvey's untimely death.
We're not done with Tera West yet. Listens-to-Wind knows her; he sends Harry her regards in Summer Knight, if memory serves, so there's another connection there. I really want a story where Tera calls the Alphas and Listens-to-Wind to protect her son. I need more Alphas.
I do think she was pregnant at the end. I don't think Jim would've added that bit about his bloodline never ending and having him be in a committed relationship for no reason. I don't think we've seen that child yet, but we might in the Young Adult series.