If anybody has any ideas lmk

So I am currently 15 days late for my period. My cycles are always 30 days apart. My last period was super weird too..it only lasted 3 days and I barely spotted, when normally I have a 5-6 day cycle and it’s heavyyyy. But ever since that last weird period I haven’t gotten any kind of bleeding not even light spotting and pregnancy tests have been negative. I got a faint positive on October 24th but every test I’ve taken has been negative since then. I’m not sure what’s going on but my OB says to make another appointment in 2 weeks when I would be 4 weeks late and no matter if the pregnancy test is negative or not they’ll do an ultrasound but anybody have something similar happen? Me and my fiancé have been TTC for almost 2 years in February so we would 100% love to be pregnant right now but after almost 2 years I’ve learned not to get my hopes up..