Im 22 years old & this has happened to me, it has only been for the past 4-5 months that my cycles have been regular, for me i changed my diet and exercised a lot more, perhaps try that also there pills you can get over the counter, Vitex Agnus-Castus they are called, they help maintain female hormones and helps regulate your period as well as the pain.
I am going through the same thing I haven't came on in 44 days I'm 36 years old this has never happened to me before and I'm stressing I went to the doctor and they took my blood and my thyroid level came out normal but I've been gaining weight and tired fatigued and Moody I don't know what to do I don't know if I should go and get an ultrasound on my throat or stomach thank you for listening
Glad you can't be pregnant as that is stressful (penis must go inside your vagina to get you pregnant) but sorry you are currently irregular. Not sure why your having longer and longer cycles but your hormones must be adjusting. If you find it getting longer and longer and you are gaining weight, have dry skin, are moody-- then get your thyroid checked. Otherwise, some women have longer cycles and some do so just for a while and then it goes back to the shorter cycle. So, time will tell. You can always consider birth control to regulate things so it is predictable AND keep you safe in case you and your boyfriend decide to have intercourse. Anyway, good luck