I've taken multiple pregnancy tests, and they keep coming back negative. I am over 2 weeks late. Whats up?

Non-ovulatory cycle. The most likely reason is you didn't ovulate in your last cycle, but there's a long list of other possibilities. A doctor should be able to help you start sorting through the list.
Maybe yes, maybe no. Firstly, if your periods are irregular to begin with, it is probably meaningless. If your are very regular normally, it may be meaningful...Or not. Wait another 10 days. If no period, doofus drug store pregnancy test. If positive, or still concerned, call dr. Gyn.