I used Ashara exclusively from when I got her to about mid way through Corelia (when I brought Xalek out for a change). I levelled as a Madness specced sorcerer and Ashara was perfect. She's not a tank though, so you have to adjust your play style accordingly, which means against strongs and elites, you send her in first to grab the initial aggro. With bubbles on yourself and Ashara, outside the tough fights you shouldn't need to dish out much healing, just focus on single target dps and renewing her bubble. When I hit 50, I found myself using Xalek more, mainly because he was very easy to gear up with my hand me downs, and he made Section X dailies a bit safer. Now I've got HK-51, so Ashara probably won't see much action. I dislike levelling with a tank, as it's just too slow, and using a healer companion when I'm a sorcerer would be pointless.

Good job on the summary of the problem. I got the next set of Kira dialogues after completing Act One, think I was around level 35, but it was clearly triggered by the class story progression rather than my own level. I had taken the dark side flirt option (after the fix thankfully), and had a number of flirt options in the new set of dialogues. If you avoided all the flirt options in the original Defector mission dialogues though, I still wouldn't give up hope of romancing Kira. This is pure speculation, but I would try giving her some courting gifts, and wait for the next set of dialogues to trigger. It would be unlike Bioware not to give you a chance to change your mind .

I left Balmorra ages ago. I've experimented using Doc a few times, but it just makes killing things too slow, so I'm back to using Kira. As a guardian, if you feel the need to use Doc on a regular basis I think you're doing something wrong.

There are certain key steps in the story line that open up the Kira romance dialogues. The first is after finishing Nar Shadaa. This is when you get the dark side flirt option which was originally bugged, plus a first kiss . The bug was fixed shortly after Christmas so you don't have to worry about choosing it anymore. I chose it shortly after the fix and haven't had any problems. The next key step is finishing Act One which opens up your legacy and a bunch more dialogues with Kira. You will most likely do this somewhere around levels 33 to 35, depending on how many side quests you're doing. If I recall correctly, this was at the end of Alderaan missions and before you head to Balmorra. So the key message is not to think you're bugged like it seems many do, just because you've not progressed your class story far enough.