On Nexplanon, possible pregnancy.

After being on Nexplanon for about 3 months, I've only had sex when my boyfriend came in my twice. September 23, 2016, and today, November 2, 2016. I've read things about cervical positions since I noticed mine was really hard, tightly closed, and barely reachable for a week or so now. I've been bleeding since I got the implant but today I haven't seen any blood at all. Could I possibly be pregnant, obviously not from today but from the sex on September 23. I know cervical position isn't a reliable source of finding out if your pregnant but it's still bogging my mind. Thanks for any advice/help.