What Are The Signs Of Pregnancy?

Hello I am having problems with pregnancy. I don't want to be pregnant yet 3 months ago was the last time I had intercourse with my fiance that was august 15 I came on my period august 22...It was normal lasted about 4 day of blood and 2 days of brownish discharge until it went away...then September 27 I came on my period normal with cramps and breast sores. but my period lasted for about 3 days bleeding and 2 almost 3 days of brownish discharge. Then not October but November 1st I came on my period again with cramps as well but this time I was nauseous and vomiting a few days. My period went away in 5 days 3 days of blood and 2 days of brownish discharge. I never thought about pregnancy until a few people joked around saying I was pregnant. I took two pregnancy tests while on my period and one 4 days after my period and all were negative. Right now I am having this tight feeling on my lower abdomen and from time to time my lower back hurts. If I was pregnant I would be 14 weeks by now but my belly isn't growing and my weight still the same I'm not as hungry as before I eat and get full really fast and also my stomach growls constantly I don't know if its all in my head and I'm having fake pregnancy symptoms?