When I conceived Marieke, (DD2), I had a high temp for the first 6-7 DPO, then it dropped, and then went below the cover line at 10DPO - I thought for sure this was NOT a good month. But at 11 DPO it went up, and at 12DPO, I got a BFP.
Maybe your chances are not gone? Did you do a test ever? All the best!