What Causes Frequent Urination And Heavy Menstrual Period?

I have gotten 2 periods one regular and one heavy but short within the past two weeks. I have had sex about 5 weeks ago where neither time they had finished, but one was without a condom and one with. I am also on the pill but may have missed one one day that week. I have been urinating frequently (maybe due to more water intake? Or a UTI?), been dizzy a couple times, had more headaches, been tired by early evening, and have had heart palpitations. Could I be pregnant? What is the possibility?