Here is a little summary of what I was going to tell you .. I only looked at actual clinical trials ...
The only human study in males investigating the effects of Vitex Agnus noted that 120-480mg of a BP1095E1 extract failed to influence testosterone levels after 20 days of supplementation, despite influencing prolactin.[38]
Most of its effect targets prolactin and progesterone
Many studies say it needs to be taken for 6 months to notice benefit
It has mostly been researched in Europe . Especially Germany .
Many studies .. results were discredited through various biases
There was a mention that it is not advised to take in combination with other hormone therapy ...especially contraceptive pills which suppress the endocrine system . In this instance vitex will be ineffective .
its long term safety and efficacy has not been clearly established and its use has been primarily in menopausal women . In this group side effects were low and vitex was taken as a replacement instead of hormone therapy .
You could contact the manufacturer directly .. they may be able to guide you and provide you with more recent clinical trials
and my doctor isn’t really helpful, she just prescribes and does a blood test occassionally but she doesn’t really care. All she parrots is that too much estrogen will cause breast cancer 
