First time going to the Gynecologist..

So I went to the gynecologist for the first time a couple of weeks ago because I had a terrible UTI that was putting me into tears that lasted 2 months . I go and everything was fine I filled out paperwork and they called me in quick . I go to the nurse and she asked me when my last period was . I told her May 16th . My period is late by months but I told her that’s common for me like last year my period was late for 4 months . She gives me this nasty look and goes “ are you sexually active? “ I said yeah I am . She goes “ are you pregnant “ I said no because I knew for a fact I wasn’t . Me and her had a full on back on forth argument of her asking me if I was pregnant and me saying no . It was ridiculous. I had to do a urine test anyway and it came up negative but why does she have to argue with me about if I’m pregnant or not .