Ovulation Confusion

Madilyn

So this month my predicted O day was suppose to be the 18th. I started testing around the 11th or something and I ended up getting a positive on the 14th. Then I started getting lighter and lighter tests so I assumed we were done for the month but on the 20th I got another clearly positive test so now my calendar and predicted period days have shifted. Is is possible to ovulate twice? Which day should I base my TWW off of? Thank you!