Positive opk still negative hpt

Kim • 27/vet tech/ married 8-18-13. Lost our daughter 6-7-16 at 41 weeks
I've gotten positive opk tests a week or so ago, took a hpt today BFN but checked a opk and it was positive again.
Was trying to figure out if in early pregnancy opk still detects as positive, any ideas?
Been feeling a lot of symptoms