I Stopped Taking Birth Control End Of December 2014 For

I stopped taking birth control end of december 2014 for financial problems. However, I had consistent sex in January with a long distance boyfriend. I didnt get my period the month of January but early February. My cycle has been semi fine since then but always a couple days late from previous days I started the last couple of months. The month of may my period was 2 weeks late but I figured that was from stress, then i had sex once with my boyfriend and it was late another week. I didnt get my period till around the 19th of May. The next month the day im supposed to start is always delayed a bit. My last period was June 25. I had consistent sex for about 2 and half weeks with my boyfriend due to our long distance relationship, I assumed I was supposed to get my period on July 25 but still havent gotten it. i took a 2 pregnancy test about 4 days after July 25 and it came back negative. however, I have very very sore breast, which is common pms for me since not being on birthcontrol and headaches which is also common. I also have slight cramps that come and go almost every single in hope that my period is coming but they end up going away and my period is still late to this day. I am not sure if i should wait till around the 25th of August for my period since in Janurary after having consistent sex for about 2 weeks i did not get my period at all. I am under the impression since i recently been off birth control my period is very irregular and my easily stressed personality can delay my hormones drastically. My slight cramps and sore boobs are worrying even though the pregnancy test i took was negative. Any thoughts of what you think could be the delay in period?