Is she pregnant pls help

Hello, I was wondering if someone could help clear things up for me because I’ve been really stressed. My girlfriend and I had sex for the first time on February 16th. We used a condom, and she is also on birth control.

Lately, I’ve been worrying that she might be pregnant because she’s showing some symptoms. However, they are also symptoms she usually has. She got her period on February 28th, which was 12 days after we had sex. I should also mention that her periods are already irregular.

Now I’m feeling anxious again because this month she’s about three weeks late. She’s showing some mild symptoms like slight weight gain and cravings, and I can’t stop overthinking everything. I’m just really stressed and would appreciate any help or clarification.