I used the dollar store test with my son the day after my missed period and it screamed positive. I got a few different of the expensive ones when I hadn't had a period after my son (he was 5 months at the time) and they were all negative. Had to go to my doctor to find out I was pregnant with my daughter. I'm definitely sticking to the dollar store ones
to be honest I got a cheap on from the dollar store cause I didn't think I was pregnant I got it November 18th (my son's birthday) and took about 3 days before my period and I got to lines one very faint I'm now 8 weeks pregnant