Period after pregnancy?

How different is your period after pregnancy? I had my son in May and got my first period June 23 and it lasted til July 1st. My husband and I did have sex 5 weeks pp, we used a condom but I was unaware of how fertile you are after pregnancy 😬...I’m just getting a little worried since I’m already a day late, but also wasn’t sure if my cycles can be a little off for the first couple of periods after pregnancy. If it doesn’t show up next week I’ll probably take a test