43 yo male. Testosterone is 299 on 260-1100 scale. Feel low, anxiety, sleep issues, dizzy. Dr. stopped HRT after five years. Is this all related?

Cause of the problem. If your T of 299, it is in the normal range. I doubt that "low T" is the cause of your symptoms, but if you want to explore hormones, then you should see an Endocrinologist and look not just at testosterone, but other hormones too.