Pregnancy Scare or False Alarm ?!

I'm 18 & I stress a lot . I had my last period in June & today is my first one since then. I took a pregnancy test on August 5 that came back positive I told my boyfriend and he thought I was joking about it. I just overlooked it as well thinking it was false so I continued with my exercise routine & our sex life. Last night we had sex and it was a bit painful and I went out a bought another set of pregnancy test because I was worried at this point they came back negative. Now my period is on this morning . I'm curious as if I was seriously pregnant and didn't take the proper steps or was it just stress , exercise & sex delaying it ???