Whats wrong with my body?

I sometimes have irregular periods but I haven't had a period since December 4th and that isn't like me at all. I was having periods every 28 days for 6 months and since I had a lumpectomy (tumor was benign thank God) my period has been absent. Today makes 71 days since the start of my last cycle. Has this happened to anyone else and if so what caused it? I have a Drs appointment in March that's as soon as I can get in. Ive took a few pregnancy test and they are negative. Im just super confused on what could be the problem. I know no one are Drs and I'm probably just not ovulating but my cervical fluid still gets the egg white stretchy texture. Please some insight?