Help 😩 Birth Control & Plan B

Is it ok to take a plan b pill on birth control even if you haven’t missed a pill ? I had unprotected sex on Friday which was on my fertile week and Friday also exactly marked a week of me being on birth control, which is how long it takes to kick in. I wanted to make sure I was safe, so I took a plan b pill while on birth control even though I haven’t missed one pill. Is that ok ? Also I’ve been feeling sick and nauseous and my breasts are sore . Its been 3 days since