Can I test?

I am currently having anxieties about being pregnant. Even though the chance is so small, because I have been on combination birth control pills for almost a year and me and my boyfriend use a condom every time we have sex. I take my pills at the same time everyday and have only missed one pill a couple of weeks ago. Two days ago, I noticed I’m having light bleeding that’s like dark brown but only see it when I wipe. I’ve also been nauseous, having back pain and bloated. Could I possibly be pregnant? I start my placebo pills next week so I am supposed to get my “period” next week so I’m not sure why I’m bleeding.. Am I able to take a test right now or would it not be accurate? I’m really freaked out!! :((