i dont understand who i am

its all so confusing. i dont know who i am as a person anymore. my personality changes depending on the person im currently with, and when im alone, my personality is the one i last left off with from the person i last interacted with (if that makes sense). i dont know who i am anymore. im worried that the people around me will influence me so heavily, i start acting in ways that differs so much from what i truly am. i dont want to lose or forget my original self. i feel lost.