With regards to being guarded toward people you don't know,please know that therapy doesn't start this way - with a dump of your intermost secrets. It's starts with talking about everyone else in your life. Over time, report builds and this person is now a friend firmly committed to seeing you succeed.
A note on choosing a therapist -find an actual doctorate that could prescribe pills (speaks to their level of education) but prefers not to. They often state this in their bio/website, and this way you can avoid any pill pushers, while getting the highest caliber of advisor.
I wish you luck, King Adepressedthrow.