To be or not to be Pregnant

Patient: Hi My name is Lindsey and I had a question about pregnancy. My fiance and I are sexually active and always use contraception (condoms). Last month my menstrual cycle started on the 19th and ended on the 22nd of December. I was expecting my period to start around that same time frame and when I counted it was 34 days. I was last sexually active on the 20th of December and still haven’t started my period even though i had my usual signs I was. I took a pregnancy test on the 28th which was negative, so i am very confused as to what is going on. Could someone help?