Girls, Weird period? Help?

So this month I got my period... But I'm not really bleeding. And what's coming out of me looks dark and not very bloody. I've been having normal period symptoms though (mood swings, cramps, and sweet cravings) but my period looks really weird! Can anyone help shed a little light on this? I'm a little scared.

I'm also going to add that I've been really stressed because of a class for 3 weeks now if that's anything relevant. And I've had sex like twice this month, both protected, I'm also on birth control and I kind of "switched" what I was taking because the pharmacy I went to for school gave me different pills than my usual for two months. This is my first month back on my former brand of pills.
Girls, Weird period? Help?
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