Particles floating in urine

Okay ladies, I've been experiencing a strange thing lately. Of course peeing in a clear cup to use tests I've noticed these small bits or string like particles floating in my pee. I've of course googled it and common things are UTIs, yeast infections, and such other things I have no symptoms of (since I've had them before I think I would know) one thing was also a symptom of pregnancy but all tests have been bfn and af is due around 19th or 20th. Has anyone else experienced this?