adjustment disorder

People always tell me that I can adapt myself very fast to a new environment,
I think the same way too!
However,
I found that although I can adapt myself easily,
I don't "adjust" myself easily.
I realised that I am not a people person,
I only live in my own world and I always want thing to be in my way.
I always doubt myself whenever things don't seem to turn up right,
I then be easily affected.
I doubt if I have chosen the right path,
I doubt if I am suitable for it,
I doubt whatever that come to my mind!
Then I will tell myself to hang on,
convince myself to stay calm,
but I found that eventually I will be overwhelming and stressing out!
I actually doubt that am I right to convince myself for hanging on!
I am not sure whether it's right or wrong,
I am not sure if I should be carrying on,
I can't convince myself,
but I can persuade myself,
and eventually I will just be freaking out!

I need guidance!
and most importantly,
a consulting session!