Why do I feel pregnant but test come up negative??

Normally I'm never wrong about it. I have a great institution about it ?? So idk,I really don't want to be but not that it would be a bad thing. But I keep wondering if I'm just way to early this would be 7th pregnancy. 5th kid. Like I did get tied, be my doctor remove one tub do idk if it's even tied or anything. .I read online that if u have a open space they can swim and you can get pregnant. So after so many kids I should know you know, but I keep saying is not possible and it's just in my head. But I feel it. Could it be possible sense doctor took one out and I only have one tied?