concerned!

I'm 19 and finished my period about 8 days ago and that same day my boyfriend and I had sex - we used protected and he pulled out because we always do. I'm also taking Gildess fe 1/20. I have missed 3 doses just in this past week. I missed 2 days and then 2 days on (I bled for 2 days after I missed and then stopped bleeding) and then I missed this past Friday (it's Sunday now) and took 2 yesterday on Saturday. Well yesterday I started spotting like for 2 hours?! But it was over then and usually when I miss a pill it's like a day or 2 of bleeding. Is it possible for this to be implantation bleeding in just 7 days? Or is it because my hormones aren't used to being this unbalanced? Also my boobs feel heavier and more sore but that honestly could just be from stress and I'm on steroids from being sick. I also had a blood test Friday morning and all my blood levels came back fine with no signs of pregnancy so can someone give me some advice or tips or what do u thinks going on?!