Help I think I’ve messed up!

Hi guys, it has just dawned on me that I may have messed up my pill. I take it religiously every day at the same time or thereabouts, however last week I went to pop it out and (my fault) I was standing in the bathroom and it fell down the toilet, so I took a pill out of my spare pack that I received from the school nurse early last summer (unopened pack). I have been having sex but my boyfriend never finishes inside me, am I protected? I’m meant to get my period next week on Friday. I’m freaking out.

UPDATE

I’ve just checked the pill packet that I used and the expiry date says 01/2018, does that mean January? Or the 1st of jan?

I took this pill on Christmas Day, am I protected?????