OPK peaks

I’m new to OPKs so if someone could explain this, I would greatly appreciate it! On 1/27 I got my first positive (test line was darker than control line) and my husband and I BD that day. 1/28 my test line was still darker than control line and then 1/29 the test line dropped some color and was the color of the control line. So I’m assuming that I must have ovulated either on my peak day (1/27) or day after (1/28)?