New to this!! nitrofurantion affecting my cycle


so I was prescribed antibiotics for a kidney infection 12 days b4 my cycle was due to start. Which I took for 6days followed by another course of different antibiotics for 5 days. All were finished Wednesday and my cycle was due to start Thursday. Now it's Friday evening and still no sign. Is this just because of the medication and kidney infection or can I hope it's something more exciting. Been doin a lot of reading and a lot of conflicting information. However I'm holding on to 'It will only effect your cycle if u start taking them b4 O. (which I didnt).