Late ovulation pregnancy

I have a fairly irregular cycle, but af usually comes around cd 33-35. She was late this month (which isn't that weird for me) the longest cycle I've had is 43 days. DH and I had unprotected sex on cd 39 (no af) and I tested negative on cd 46. Now it's cd 49 and still no sign of af. I have a little bit of bloating and a little bit of a back ache, but those could easily not be related to any of this. When should I test again? Or any other thoughts? If we concieved on cd 39 should I wait until cd 53. I thought for sure I wasn't pregnant, but now I'm not so sure.