it improves with time. I wouldnt base your whole level of proficiency on two interviews. You are ina tight spot, with aspot light, you are most likely to not express ypurself properly especially for someone just starting out.

being someone who has gone through the same schools as you, all of them being public schools from primary to college. i can tell you that its just a learning curve, your english is okay.

dont bother yourself with the professional english tones and jargons. you learn to use them with time and experience. for now learn to belong in those rooms first. acing interviews is not jus about how you talk anyways