Birth control


I'm 19 about to be 20 and my mom came into my room yesterday to find my old borth control pills on my dresser. Today she came into my room saying " so I found something...some pills" then I had to explain everything and lie about why I'm taking them. I told her it was to balance my hormones, which isnt a complete lie but also not the whole truth. Shes always told me to take care of myself so I dont understand why shes so mad. I dont want her to be mad, should I try and make her understand or just let it be?