Late period while on the pill. Please help!

Okay so I'm a bit of a worry wart, but can your period come late while you're on the pill? I'm sexually active and since I'm only young I always worry that I could be pregnant. My boyfriend hasn't finished inside me and I haven't forgotten my pill, but it was supposed to come today and it still hasn't come. It's 8:30 at night and there's still nothing. I know it hasn't even been more than a day, but can it come late? Knowing it can might make me feel better. If it doesn't come soon though I'll definitely be going to the doctor. 
Ps, please don't give me a lecture about having sex while I'm still young. I'm very safe and it's my choice not yours