Help! What do you think is happening to me?

Hi ladies ok sooooo last month I did the BD everyday that glow told me to. I took opks and I think I had a positive during that time. I got a uti, had to get on antibiotics, then got a yeast infection. Now I am 3 days late for AF which is VERY regular I almost always get her on the 4th of every month. I took 2 pregnancy tests and they both showed negative. I always cramp up day before AF and I have had no signs of cramps. What do u think is going on??? Could the uti n antibiotics have thrown off my cycle?