Pregnant? Please help!

I started birth control (lo loestrine fe) at the beginning of June. I always take my pills within 2 hours timespan every night. I was told to wait one week before having sex without a condom. So during the middle/ end of my second week of the pill I had sex without a condom several times. Starting middle of the third week I had spotting. It continued for 10 days. Since it went on for so long I don't think it was implantation bleeding but I'm not sure. I was wondering if it could be implantation bleeding? Spotting from the birth control? Or my "period" early? Since it's lo loestrine there are 24 active pills, 2 half dose, and 2 placebo. I just finished taking the two placebo and am starting the new pack, this is when I should get my period but I haven't. So that's why I'm wondering if there is a chance of pregnancy or not. I've also been nauseous and light headed, but I think that's just the pill.