Opk question

💋🥀Angel👼🏾🙏🏽🤞🏽

Ok so this morning I took a opk and glow said it was positive

I just took another one and it says negative

So does that mean I already ovulated (today) or was the 1st test not positive? I took letrozole 7.5mg this cycle and I’m on CD11 today... Help please