15dpo and still for AF or BFP

Hey all. Just looking for encouragement that BFP is still possible. I ovulated on day 12, had well timed sex, and temps are not below cover line yet. I'm on 15dpo but even with most sensitive preg test, not even faint line. I have not had cramps or much for PMS except for some irritability (I have a busy toddler though!!). I tested pos with my son on 12 DPO with most sensitive test so I guess I'm discouraged about the lack of similar timing. Anyone have similar issues? Thanks!