My pregnancy test didnt come back positive until i was 5 weeks pregnant, almost 3 weeks after my missed period
Three weeks after a missed period would make you 7 weeks, not 5, Dani.
I have never had any issues getting a positive on an hpt on or before the first day of an expected period but some people who ovulate later in their cycle may not show a positive for several days after. First morning urine is best, and there's no need for expensive tests (the ones at the dollar store are just as sensitive).
I done 2 tests both come back negative so i left it a few more weeks n took a clear blue and it come back positive i was only 7weeks gone and im now 17 weeks gone :)