What’s going on??

So I’ve been on birth control for awhile now. Coming up on 2 years. Before birth control I was always regular and had a longer period but I never missed a period in the 6 years of having one. In August I was given the okay to try to skip periods with my pills. It never work or just delayed it for around 2 days. Never been less than 30 minutes late on my medicine. The last time I had sex was a week before my period and how I’m 20 days late. I got my acne and all my pms just no period?