Ovulation and the mini pill. Help

So I know that with the pill some people show symptoms on ovulation and some don't. Well I'm new with norethindrone 0.35 this is my 3rd pack and i already missed my period this month and now I'm ovulating, so I don't know how this really work. I'm worried because I'm seeing my bf this week and we don't use condoms, do you think that the pill might not be working a 100% or something ? Please help:(