Hello emmascalpello. Thanks for visiting healthcaremagic.com. Any change in your birth control can change your period timing and your bleeding. Any time that you forget to take your pill, you change your body chemistry and open the possibility for pregnancy
. Any time that you take other medications, besides your pill, like antibiotics, it decreases the efficacy of your birth control pills.
You could be pregnant and unfortunately, the urine tests can be unreliable if not taken at the right time. I would advise a blood pregnancy test at your physician's office.
Be well, Dr. Kimberly