Over analysing?

Jessica • 24, England, implant out in Jan 2014
I had my implant out in January and had a light period on the 26th of Jan, my next period was 26 days later on feb 16th and then another 21 days after that both of the last periods were completely normal in regards to flow. Before starting on the impant 2.5 years ago my cycle was fairly short although I'm not sure exactly how short. 
​I have been having a few symptoms but wonder if it's all in my head nausia, painful nipples lower stomach pain on the right hand side and slightly tender. If I am going on my last cycle my period is late I have done a test which came back negative. Even if my period was due fairly soon I normaly have incredibly painful breasts before hand. I have had some cramping two days ago but NOTHING.  I don't know if maybe I should presume my periods are irregular or if to test again it when!?! Any help or advise/support would be greatly appreciated. Am I just driving myself mad?