How did you first know that you were pregnant ?

I recently got off Depo in may been on it for 6 years straight. June I had a regular period then comes July where I had my period for the whole month , August comes no period at all and now it's September and I recently had unprotected sex 🤷🏾‍♀️🤦🏾‍♀️ 4 weeks ago and still no period just wondering if I'm thinking to much ? Did my cycle change ? Am I stressing ? Or am I pregnant ?