Chnaging brands

I have a question about changing brands. Last month, I was on tri-lo estarylla but experienced irregular bleeding. My doc prescribed me Previfem so I started that after my placebo week. I had sex without a condom sometime between the first 7 days of taking it and I’m wondering if I was protected at the time. I read my pamphlet and it didn’t tell me to use back up for 7 days, only if switching from an IUD. It’s day 3 of placebo week and I still don’t have period, a bit worried. 😭