Birth Control Question

Jess
So I've been on birth control for almost two years. Over the past two weeks I've taken a few pills a couple hours late. I've had unprotected sex with my boyfriend a few times during this time. But each time he pulled out. 
I had my period a few days ago. But it was late and it was only like three days. Normally my periods are 4-5 days. 
I started feeling nauseous a month or so ago but It only happens when I haven't eaten for a while. 
After reading this, does anyone think I should take a pregnancy test? My boyfriend and I are really careful. And I'm convinced that my period was a period and not spotting. I'm just a little worried.