My concern is that they might not make her a companion because I find it easy to just not side with her, games sort of pushes that.
Yes, this is true. As most people tend to play "good", Larian have pushed you away from the evil path ( i.e. embracing the tadpole ) at every opportunity, presumably to avoid upsetting players accidentally. This was a little counter-productive when they were asking EA to take/test the "evil" path; it took me 4 plays to successfully be "evil" in this game!
Yes but are you sure it is the evil path to not use the tadpole? Some of the narrations really leave that up in there air. Like the narration about you body wants her gone, maybe that is the tadpole that is making you feel that because it fears her/him? When you take things like these dreams, and the use of your psionic abilities as a given, to NOT use them because you THINK it is the evil path, leaves you wide open for a twist. The truth is, we do not know if it is strictly the tadpole in your head trying to corrupt you. It has been stated that they tadpole was not the ordinary tadpole, so the truth is, we have no idea what it's agenda truly is.
Also, there is ALOT of people that like to play Renegade, and sometimes it offers the best story. If you are limiting yourself to just good characters you are cheating yourself.