Advanced Digital Ovulation Test

I have been using the Advanced Digital Ovulation Test this cycle. The first time I used my test on CD18 it indicated Peak fertility with the solid smiley face. I was having other symptoms of ovulation at that time. I had two packs & I decided to use another one the next day out of curiosity and it came back with a low sign. However my temperature shifted and my BBT chart confirmed ovulation and my temp has stayed high. I have then done the test each day since then and have had the flashing smiley face indicating high fertility even though I am now 8dpo according to BBT Chart and CM etc.
Can anyone help me as to why this is happening? I am so confused with these tests!!
Could it possibly be indicating pregnancy?? Or should I just stop using them this cycle and take it that the first Peak that I had was wrong and I haven't ovulated... Even though my body and temperature is telling me that I have?! Confused!!