No period

Well, let me start by saying ive never been irregular. Here’s the big BUT, in October I had my period as usual, then I skipped November completely, had my period in December, now it’s almost March and I haven’t seen my period since December 12th.. I’ve taken test after test with a negative. My fiancé and I are ever so trying to have our first bundle of joy. But something just isn’t working in my body. Does anyone have ideas or went through something similar.