Talk to Gynecologist on Fertility Problem

Hi, I m married woman, I had my last periods on 17june, now its 21 july and I have not got periods yet, at 20th july moning, I tested through hpt , it showed only control line but that too very faint, I have pain.in my body, espacially legs , bck n abdomin on and off, I m confuse as if I m pregnant or just my periods are late, as I always get periods on exactly my date, I bought my strip many months ago so I m confuse whether strip was invalid, please explain, and I m ttc from many time and had fertility treatment back in march 2019' please help