My last normal period was July 19th.I had intercourse on July 26th. We used a condom,which had not broken. But for back up, I took Plan B. And bled like a normal period for about six days. Whats the probability of being pregnant?

I just answered your question here: https://www.empowher.com/community/ask/normal-period-was-august-19th-had-sex-26th-used-condom-didnt-break-and-took-plan-b-bac#comment-67153

Since you had your period July 19th, I assume you are expecting your period to begin this week?

Condoms are 98% effective at preventing pregnancy when used consistently and correctly, so your chances of being pregnant from one episode of protected intercourse are very, very slight. (Nothing is 100%).