Implantation bleeding?

I am going to schedule an appointment with my doctor, just want to hear your opinions to try and ease my mind.. currently have a 2 month old baby & my partner & I decided to use condoms as birth control (used pull out successfully for 6 years). Well my partner didn’t pull out or use a condom about 2 weeks ago (October 21st). I took an emergency contraceptive pill before the 72 hours hit. I got What I thought was my period on Tuesday (October 31st). It was was heavy like a period, but my period usually last 5 days, this only lasted 3. Could it have been implantation bleeding? It’s the fourth day, but ‘my period’ seems to be completely gone. Any help is appreciated!