<human>: Hi, hoping its okay to ask this here. I'm a 22 y/o white female (5' 9" and ~160lbs) living in the Chicago suburbs and I've been on the combination pill (Lutera) for almost 4years. I am not taking any other medications or supplements. Usually my flow lasts for 5 days and is light but definitely noticeable. Over the past 3 or 4 months it has started to lighten significantly. Last time I menstruated for very lightly for 3 days. I know loss of your period is one of the potential side effects of hormonal birth control but I kind of thought that would happen sooner if it was going to happen. 
I guess my question is: Is it "normal" to start losing your period this late into taking combination hormonal birth control or should I set up an appointment to talk to my regular doctor about other possible causes?

Let me know if I can answer anymore questions and thank you for your help.

Could you distill the essence of the text into 1-3 sentences?
<bot>: 22 y/o white female experiencing shorter periods after 4 years  on birth control pills wondering if this is "normal"