Hey!
I just wanted to let you know that you are not alone in this. I am incredibly intimidated by my advisor and I don't have cultural differences to blame. What has helped me is being extremely clear in what is causing me anxiety. For example, when I first started to meet with him, his expectations of our mentor/mentee relationship eluded me. Eventually, I brought it up, but only after holding back tears for out first several meetings. Definitely don't feel ashamed about not doing better. Definitely DO ask for help if you need it. Faculty understand that we are still students and not perfect, otherwise we would be the ones teaching them.
I think the key is accepting that you are not going to be perfect and by ripping your thesis to shreds, your advisor is showing that she is invested in your success. I would be much more worried if she hardly read it, handed it back to you and said it was fine and gave minimal feedback.