I’m very conscious about my age with my sex life

So I’m 24 yrs old, seriously lacked a lot of information about sex before being truly active which has been 3 months ago. I’m getting scared of getting pregnant so I start to check my stomach out if there are any changes. I have been diligently taking my birth control, but I get to have doubts and I worry. My mind goes to different places, I feel trapped in my own feelings. my health has been going weird (I got diagnosed for having hyperthyroid, I’m feeling heartburn and I’m getting a bit of belly of fat and I’m scared.