OPK as HPT

From what I have read if you have enough hcg for hpt to test positive then an opk should be positive, too. I took an opk 2 days after mc that was very positive, and one today 15 days after mc and it's negative. The only reason I used opk is because I'm out of hcg strips. 3 days ago I was at a level 53, whereas the Friday before that I was at 340, so I know my levels are dropping fast and I was curious if I was at 5 or below. I have another blood test Friday and by then I'll be at a 5 or below, I'm sure. I'm going to use an opk everyday now so I can track ovulation. Praying my next period never shows up!