No judgment, just advice please!

Hey guys, so I’ve been on the 21 day cycle birth control pill for about 8 months. On February 9th I had unprotected sex and missed three consecutive pills the day before, the day of, and the day after. February 10-12 I was red spotting so I thought it was just a early/ short period because of my missed pills. Now yesterday and today (3/1) I’m having brown and light pink spotting. Could this be implantation or just more breakthrough bleeding because of my short period last month? If it’s implantation, when will a test be most accurate?