Advice so I don't keep flipping out

Ok so, my periods a couple days late, I've been off birth control for about a month now and I had the post birth control period then. Now, I can't remember if my boyfriend and I have had unprotected sex and if we have Its literally very briefly that he's inside. He uses condoms (which I know don't always work) but he always checks to make sure nothing came out.

On the other hand I just started school and work is stressing me out. So maybe it's just stress?