What's going on with me??

So I found out a few months ago that my tubes were blocked, and due to my sexual history they've been blocked for several years now. I'm not of birth control because my ob/gyn doesn't really think I need it, and on the off chance they spontaneously unblock I'm fine if I get pregnant. I got of the depo shot in January and got my first period in April, they've been severely inconsistent since. I had dark brown discharge for like 6 weeks, then a regular period at the end of July, and glow says my period is late now. About 2 weeks ago I had this stringy, slimy discharge, it didn't get my undies dirty or anything, but my whole inner labia was super slimy and slippery. That lasted 2 days. All discharge has stopped, I was fiddling around down there last week, and what discharge I have is milky and thick, but it never makes it to my undies. I've had strange cramps and lower back pain the last week. Took a pregnancy test this morning, it was negative. Any ideas?