How soon can you get pregnant

Tatia • Mother of 👧🏽👦🏽👦🏾 pregnant with number 4

How soon can you get pregnant off of bc. I recently just got off bc on the 21 of January I was also ovulating had sex on the big day the 24 of January and on the fourth of February I had cramping and spotting for three days(irregular period) and my period was supposed to come on the 8 of this month and it didn’t took a hpt and it’s negative just trying to see what’s going on