On July 13 I got my period it ended on July 18 and on July 20 I had sex with my husband and he fully came inside of me.What are the chances that I could be pregnant?

I would assume you and your husband have sex more frequently than that ? Don't you as a married couple have sex at least several times a month ? Why worried about this one time ?

Are you on any form of bith control pills. did you use a "morning after" pill ? I assume you did not use a condom?

But anytime you have sex there is a chance, without knowing your ovulation dates ( not from online sites but from real tracking of time)

So is there a chance, yes, no way to say 40 percent or 20 percent, there is just a chance.

You will need to wait to see if you have your next period.