Hello I Want Ask Question , I'm 21 And I

Hello I want ask question , I'm 21 and I never had prop sex and I like somebody and that guy always want have sex with me and always I push away so I want have sex but always I'm masturbate and I feel orgasm today I wanted have sex with guy ( I'm female ) so we wanted he played with me and I played with he's dick but I got stressing out when we started I don't know why I got stressing out ... I don't know what to do ? I don't know why I'm feeling stressing out when I want have sex , how can I help myself ?? What I should to do ??