What Causes Missing Periods And Negative Pregnancy Tests?

I have missed a period by 2 weeks. I am always on time and have been heavy for the last few years. I was diagnosed with fibroids a couple of years ago. My stomach is now very bloated and this week I have eaten very little as I always feel full. My stomach is also making load gurgling noises. I have done three tests and I am not pregnant. I am 45 is this normal?