HELP ME PLEASE 😭

Megan
My period is late by 3 days it will be four days tomorrow. My period usually starts around the 22-24 but the past two months it had started around the 17-18. Could I be pregnant or is my cycle just switching again? I don't think I have any symptoms only breakouts and nausea but I think I'm nauseous because I'm nervous! Any advice would help. Thanks