What happens when you block testosterone from becoming DHT, Doesn't it then turn to estrogen? (Hair loss question)

Regarding hairloss. When you take something like propecia or even saw palmetto, these all (arguably) block the conversion to dht which helps to prevent further loss. But when testosterone is prevented from becoming dht, the only other option is to become estrogen which i believe is why men can get sexual sides effects and it can cause gynecomastia (I got this when i went through puberty). Is this Correct? And as someone that had gyno before am i more likely to get it again if i take this pill?