I don't know if you're still having your vertigo problems, but some other things you can try are:
Ativan (or anything else in this family), though like the Valium which is a derivative of the same family, there may be significant issues.
Gingko Biloba. This has been seen to work on vertigo in some cases, though not all, so I suspect it depends on the cause of the vertigo. I know it works well on mine, but that's all I can tell you. You'll want much more than the standard dose for vertigo - start around 300 mg spread as evenly as possible over the day to see if it works, then adjust downwards from there (or up if need be). I have NO idea how this affects breastfeeding, but it's certainly not addictive like Ativan/Valium.
What was cause of your vertigo, do you know? Because I have sometime not always, but it has to do with my sinuses.
For me, it's from Chronic Fatigue Syndrome. The exact link is unclear, but as I understand it, the common belief is that it's a virus irritating the various ear canals. Another theory that I've heard is that feedback is amplified inappropriately and that the Ginkgo in some way is very mildly suppressing some of that.