No matter what the answer is, asking questions about who you are is never a mistake.
It's a normal reaction to be scared at first - after all, it's a giant leap into the unknown.
There's plenty you can do (in addition to a gender therapist) to explore your own identity without making permanant changes.
Look into buying a binder. A site called underworks sells some good ones. It's a type of undershirt designed to flatten (ie, bind) the... errr..... chest things.
Other things that rank up there as reversable but affirming are clothes and haircuts.
Even if you wear mens clothes normally, it's just nice to have some new shirts and jackets that haven't been stretched and distorted from wearing them pre-binding.