я чувствую себя совсем одной в этом мире
I feel all alone in this world.
I feel really lonely in this world.
https://books.google.com/ngrams/graph?content=I+feel+really+lonely%2Cfeel+all+alone+in+&year_start=1800&year_end=2000&corpus=15&smoothing=3&share=&direct_url=t1%3B%2CI%20feel%20really%20lonely%3B%2Cc0%3B.t1%3B%2Cfeel%20all%20alone%20in%3B%2Cc0
спасибо!
Пожалуйста!)