It sounds to me there is a possility you could be pregnant, but I am not understanding how you could can ovulate so close to AF.
My last AF was on the 28th of January, I ovulate later than the typical person. My AF was due on the 25th of Feb.
If you ovulated on the 20th, you period would not be due until roughly the 5th of March. There is on average fourteen days from the time you ovulate to the time of your period. If you did ovulate on the 20th then it could very well be implantation bleeding .. implantation occurs 7-10 days after conception.
When did your last period start