Please can someone help me?

I'm 16 years old and have been having periods since the age of 12. They have been a regular 30-33 day cycle until recently since February this year they have randomly changed to being anything from 40-42 day cycles and now I haven't had a period since April and I am now on 54 days since the beginning of my last period. It is really starting to get me a little be worried/stressed now because all I want is for it to come! I have recently taken my GCSE exams and I took my last one on Friday just gone. I also take part jn regular dance competitions which I do a lot of weekly training for. I am confident tht I am not pregnant as I am a virgin and even though I did dry hump with my boyfriend on friday just gone I know tht nothing could of happened from tht because my boyfriend was wearing his boxers and his school trousers and I had on my knickers and school skirt. My skirt was up around my waist so I guess u could say I might as well of just had my knickers on but I also had a pad on because of incase my period started during the exams earlier in the morning so nothing could of gotten to me. My boyfriend did get a little damp patch on his trousers from his per *** I'm guessing but nothing got on my knickers as far as I'm aware so I am almost certain tht I am not pregnant. I just want my period to arrive now though because the more I wait, the more I think well what if? And I just want someone to reassure me tht I am being stupid and does anyone know of anything I can do to help my period arrive? Thank you x