What's going on :/

Hello, thanks for reading I really appreciate advice and anyone's thoughts. 
​My period is now 19 days late I haven't been stressed lately until a couple of days ago.
 My period is regular and can be heavy - when AF was due I has PMS symptoms for a good week before and about a week after, I've had slight cramping now and then.
 I took a pregnancy test when I was 9 days late and it was negative - I just don't know what's going on. I have no symptoms of anything just tired. For the past 2 days is where I've been just stressing and worrying about it. Any ideas on what I should do next? Just wait or take another test?
​Thanks for reading! X