A few thoughts here:
First, you should continue to get improvement in your symptoms after a stroke - out to at least 6 months after the stroke occurred. Therefore, I
would continue to work on this aggressively with your physical and occupational therapist.
Second, it is never OK to be falling this much. You need to work with your therapists about finding a better way for you to turn safely. You may need extra support, such as with a walker, or with coaching on how to use a wall to support yourself while slowly turning.
Finally, on some rare occasions, I find that patients get benefit from medications. These include either meclizine or low dose benzodiazepines (the most commonly known being valium). Sometimes, these medicines nicely take the "edge off" vertigo and imbalance. However, I would work with your doctor on prescribing these, as in some cases the medicine makes the problem worse.
I would add that you would probably be well off to see a Physiatrist (Physical Medicine doctor) as they are experts in stroke rehabilitation.