Tips on how to relax to allow period to come?

I had protected sex 8 weeks ago on the first day of my period and that period continued as normal.

Then, I strangely got another period only 2 weeks after my last period started (i.e. start dates: Jan 27 and Feb 12). This period was lighter (which I guess could be because it came so early) and had no clots (which i usually have). It, however, last the full 6 days that my periods usually last.

Since this happened, I did not expect another period on Feb 27th, but rather one on March 12...it is now March 18th and I still have no period.

I have taken five urine pregnancy tests since the weird early period happened. The first three were done by the doctor and the last one I took at home (this one was taken on March 20, ~8 weeks after I had sex on Jan 27)

I feel no other symptoms but I have no idea where my period is! I am hoping that since I had sex 1.) on my period, 2.) used a condom, and 3.) have had all negative pregnancy tests since then, that I am not pregnant. I am scared and I think that may be stressing me out even more, possible making my period later than it should be.

I am quite sure I am not pregnant, but should I get a quantitative hCG test done to confirm this? Any advice or ideas as to why I may be late? 

DOES ANYONE HAVE ANY TIPS ON HOW TO RELAX OR HELP MY PERIOD COME SOONER? I think it is getting more late since I am stressing over it.  Thanks!