I'm 26 and I've been on my current birth control for over 4 years and my period comes like clockwork (almost) every month and I never experience spotting unless I forget to take a pill (which is happened maybe 2x in my life). However, the past two months I have started to spot about 1 1/2 weeks before my period should start. Last month I spotted for about a week straight and this week I only noticed it for about 1 1/2 days. I've done research and some say it could be stress related and I can definitely say work has been causing me a lot of stress but I've been stressed out over work and other things before and my body didn't react this way which makes me wonder if that's really the cause. 

Any ideas on what may be causing this for the past 2 cycles? 

Thanks for your help and advice! :)