You're 15 DPO right now. Your luteal phase normally lasts anywhere between 12-16 DPO. My guess is that, if you're not pregnant, you're going to start your period tomorrow or the day after.
That's of course, if you're not pregnant. Like you said, your temps are still high, and you're having symptoms (though many of those are also the same symptoms associated with a coming period too, so it's hard to say). Did you take your test with first morning urine? Sometimes that can make a difference. It's more concentrated in the morning.
It's also possible that you miscalculated ovulation. Your temps seem to line up with ovulating when it says.. but you continued to have fertile CM for four more days after O. It's possible that you ovulated a couple days later than you thought... though, like I said, your temps line up with ovulating on CD 13, so it's hard to say.
If you don't start your period by tomorrow morning, take another test first thing in the morning.
Good luck!