I cant speak to what mechanism 17hd works through. But if this is any indication
It elevates serum levels of free testosterone
It could very well be working on SHBG, and thus causing some excess estrogen rebound. This isnt all that big of a problem, although it may cause some mood swings. I dont see any reason to fear natty test boosters, any side effects will go away upon discontinuing use.
However, your comment about not being able to workout without them is simple ridiculous. all you have been taking is a simple nitric oxide inducer, some creatine and an over priced free test booster. Its all in your head bro.