pls help me

Hey ladies just wanted to ask a question about my ovulation? The think is I got the clearblue advanced opk I've been testing since CD 8 and I got a flashing face from cycle day 12 and I'm now CD 16 and this evening it said low. I also had the Cheep ones and it was negative all yesterday but today I got a high , then this evening it's negative I'm so confuced did I not ovulate at all or did I miss my surge? Ps I ran out of the opk so I had to open a new box so I tested it with the old holder and it was flashing face, but when I test on the new one it's says low plz help plz Thank you.