late period, negative tests

my period is late and i'm confused and looking for reassurance.

my cycles usually vary from 26-32 days, most fall around 29 days. i'm on day 35 of my cycle (june 30th) with no period but lots of pms symptoms (cramping, dreams, swollen breasts). i had sex during my fertile week (according to eve, not sure when i actually ovulated) on the 6th, 8th, and 12th. all three times we used a condom, no condoms broke/had holes that we saw, and he pulled out before he came every time.

when my period still hadnt shown on saturday, i took two pregnancy tests, and they were both negative. two days later, still no period.

how likely is a false negative several days after my missed period? has anyone else experienced this and gotten a positive test later? should i retest? (i really can't be pregnant right now. i'm going to the gyno in two weeks to get on the pill btw)