With the pill you need to take into account any antibiotics you've been on, if you've been sick or had diarrhoea can all affect how the pill works. Deffo check in with Dr. Are you on the combined pill or mini pill?
@khadsnuri I believe there's only 2 types of antibiotics that effect the pill, they begin with R I think. I don't think they would've gave you them for uti. Deffo go to drs get some blood work done.
Have you been on any other medications. Taking certain medications makes your birth control less effective. Also not taking it at the same time daily and skipping a day. Also no birth control is 100 percent. I would call your ob and see what's going on