When do i stop testing?

First cycle of TTC (though not preventing since March) and I'm 3 days late on my normally fairly regular period. According to Glow, I'm 15 DPO although I haven't used any opk's so I dont yet know how accurate that is. We BD'd the 2 days before but not on the actual day as I wasn't feeling well. I've taken 2 tests so far (with blue dye) and both very negative. I don't have my normal cramps although I do feel a little tinge of it. They're usually pretty rough. Question is - when do I assume if I was pregnant, it would have shown up. Do I keep testing until AF or do I just figure my cycle is a little off this time and wait for it to show up. This is all very new to me and you guys are so helpful!