Where Did My Period Go ?

Hello All, 
​I am new to this forum but I have a question that I was wondering if you could help me with. Has anyone had their period vanish for over two months for no apparent reason ? 
​When it first happened, I was scared that I might be pregnant but I have tested myself numerous times and every test comes up negative. The last time period I had was the end of April and the last time I had sex was two weeks after that on a weekend getaway with my boyfriend who lives long distance from me. I have been testing myself worried all month and every test shows that I am not pregnant. 
​My question is, is this common and what kinds of other things can make your period vanish aside from pregnancy ? I have heard stress does which makes sense because I have had a fairly high level of stress at work but nothing out of control. Is there anything I can do to get it to return ? Not that I'm fond of bloating, cramps and PMS etc but it's nice to have that there to remind that everything is a-okay... Thank you in advance for your feedback and answers.