I Have A Few Questions, Actually. I Don't Think There

I have a few questions, actually. I don't think there is anything to worry about, but I am a bit concerned. I am 21 years old, and I had sex twice this month for the first time since the beginning of October, 2016. So I hadn't had sex in almost 4 months. I do take combination birth control pills, which I have been taking since high school (Although I have been taking Cypred for a year now). With these pills, I typically have a lighter period for 4-6 days tops. Sometimes it only lasts 3 days, and will mostly arrive when I go to the bathroom. I always get cramps in my back and stomach which has been happening to me since last Tuesday. I have been taking my pills on time every single day (Give or take between a half hour or hour of my set time every once in a while. The longest has been an hour). I take no other medications except for a woman's multi-vitamin gummy. The recommended dosage is two gummies a day but I always take three in the morning, and I've been taking my birth control pill at night. I used Trojan spermicide condoms both times this month, and they were used correctly, the entire time, with no rips or tears. I think that my period came early, which is weird for me. It came the Thursday before, so 3 days early. The period seems a bit lighter than usual, and sometimes it will only come out of my vagina once or twice a day. The blood is red and stringy like usual. It has unexpectedly been in my underwear and I see it come out in the toilet like usual. It has filled up my tampon only twice, but usually there is just some red blood on the tip and it's not usually soaked. I got my period Thursday through Saturday, and during the actual week of my expected period (So this week) I got it once Monday evening and twice Tuesday (so today). It has been especially light today and didn't fill up a tampon much at all. Should I be concerned? Does this sound like a weird period or implantation bleeding? Can my overdose of vitamins have a negative affect on my pills? Did the half hour to hour difference have a negative affect? How late is late? Is it possible that precum somehow touched the outside of the condom from my hand and got me pregnant? Please help. Thank you.