I'm not sure what to do anymore

I don't know what to do anymore. I feel like my anxiety is taking over everything and I'm never happy. I went through a situation when I was 20 and I'm now 25 about to be 26 and i still have anxiety about it. I'm on birth control and have gotten my period every month but I'm constantly paranoid about being pregnant. I'll take tests and they come back negative but there's still no convincing me that everything is ok. My mind is constantly racing t ok then point where sometimes I just feel like I'm better off dead because then I won't have any of these thoughts anymore. Idk what to do. If someone has advice or has been through this situation please help me out.