Late again

So this isn’t my first time being late the first time it was a pregnancy scare this time it might be the same thing again or could be late because of stress from school. Me and my boyfriend did have sex but we used protection and just in case he pulled out. I was wondering if it could be a factor of both or I’m just overthinking it. Any tips to help not to be worried about it? That’s all but thank you so much for reading this and giving me advice.