would like to get pregnant

I have had my tubes clamped for 6 years now. regular af. however, i have been experiencing pregnancy symptoms for the past 3 month from severe nausea to even stomach getting bigger. my doctor has ran several tests even ultrasound and i am not pregnant no fybroids no scarring nothing. I would like to have another child but i dont want to go through wondering every month if there is a possiblity from thee symptoms. could i have some sort of hormonal imbalance oro wats goin on