Was the one day good enough?

So I bd on the 15th but I didn’t test my ovulation cause of lack on money to buy any test but on the 17 that night going into the 18th I got the money ran to Walmart and bought the test and took them right away it was positive as the test line basically took up all the dye from the control line it was barely there so I took one the next day and it was negative and been negative since then my question is was the one time on the 15th good enough? Oh according to my apps it said I was to ovulate on the 18th so the negative test did confuse me I didn’t go buy my cm as it’s always been creamy cm so I use preseed and continued to insert preseed til after the 18th just in case the little swimmers needed more help