I have been sexually active with this guy, who is my friend, so it's a friends with benefits gigWell....your attitude regarding pregnancy is a bit disappointing. I never like when someone asks for advice...but then tells the advice givers what they can and cannot say.Before anyone gets on their soap box i know that's stupid blah blah blah.. but possible pregnancy scare isn't really my main concern with this issue
Now...with that said... I'm kind of wondering if the light brown spotting, lower back pain, heavy discharge isn't ovulation..........not period. Perhaps your ovulation was delayed this month for one reason or another, and you're just now ovulation...which means actual period will come in 12-16 days. The heavy discharge definitely makes me think that, especially if it's not discolored or foul. Of course it could also be a bacterial infection or an STI. Just because someone comes out of a long term relationship doesn't mean they are STI free. You're trusting another human being, whom your friends with, with your livelihood. Also, not every woman stops her period completely during pregnancy. It is not uncommon at all for a woman to have spotting when she would normally have her period, therefore think she's not pregnant and later find out she is.
If it were me? I'd take a pregnancy test today. And if it's negative, I'd change my views on protection asap. I do not take hormonal BC either. But I do chart my cycles so that I know when I'm the most fertile. I abstain from sex on those days altogether. On the other days, I use condoms. But there are other options out there like the diaphragm. The book "Taking Charge of Your Fertility" by Toni Weschler changed my life in regards to understanding my own fertility and how my body works. I don't plan to ever go back on hormonal BC unless for some reason I'm medically required to. Go take the pregnancy test.