Im feeling incapable and useless

I got my first job but im feeling so useless and bad . I got the job from a nice friend of my mother and ive been working there for a month and a few weeks , but I still make a LOT of mistakes . Before getting the work i used to spent a lot of time alone in my house, using a phone and stuff, also my routine was always the same. My mind and thinking got slower because of it i guess ( I already was a slow but it got worse with time) and I have been making mistakes that could have been easily evitated by other normal people .Im feeling like a invalid cause my attention sucks and feel kinda deteached from reality .I also feel like im emotionally distant from my boss , the others feel comfortable and talk normaly with her ,but i feel so distant and i feel kinda afraid of her even if she is a good and patient person .I also didnt thanked her enough for what she did to me .I feel a lot weaker when compared to the others who I work with cause I still suck at doing things and feel overhelmed easily , sometimes paralyzed in fear .my posture easily shows that im vulnerable ,shy and insecure and people seem to talk more soft to me cause they know im more sensitive , I hate being this way , I wish i could be more open and free with them so they coud treat more like a equal , I wish I were like them . I feel so off and far from everything and everyone , I like this work and all but I still suck at this and I like the ppl there but i dont want to disapoint them, I want to get better but its hard cause my thinking process is slower and i take a while to figure things out , its something hard to control , How do i fix myself?

(Sorry for the long text and bad english its not my native language)