No, if you tested on Day 13 and it was negative, it may well be wrong. A lot of women would test positive at that point, but not all, especially if implantation occured later than Day7.
Ive known women test on Day 13 and get a negative result and go on to get their BFP that cycle....I myself only had a VERY faint positive with my son on Day 16, but that was with a Predictor test and they are not as sensitive as some of the tests on the market.
Lotsa


