Missed period, test negative

Hi everyone,

I hope I can post my question on this forum and put it in the right category.
I have a 2.5-year-old daughter and I haven't taken the pill for 1.5 years because my niece has breast cancer (the pill increases the risk) and it didn't feel right to take it anymore. I wanted to get my natural cycle back, and that happened right away. I always got my period on the same day with no problems. But this month, my period suddenly stopped after it was already 4 days late. I usually have quite a bit of trouble with ovulation, I really feel it, and I felt it this month too, but as of today, no period, nothing, no sign at all. I took 2 tests and both were negative, not even a faint line. However, I've had 2 intense PMS episodes in the last 2 weeks. I've had this for years, and it was quiet, but suddenly it's back. Even though in previous years my period always came on time, this time it hasn't. I haven't been feeling completely well the last few days, my stomach feels messy, I'm nauseous, and sometimes I get intense diarrhea out of nowhere. My stomach is very bloated, and somewhere in my mind I think I might be pregnant, but the test says otherwise. I don't know what to do with this. Does anyone recognize this? For clarity, a second child would be welcome. We had planned to try again in the new year. We've been using contraception in the form of a condom for the past 1.5 years.
Does anyone have any idea why the period is late and this feels familiar? I'd love to hear from you :-)