I’m 18 and I’m unsure if I’m pregnant or not.

I haven’t had my menstrual cycle in 2 months. A week after I missed my cycle, I went to the doctor and they said I was not pregnant but the doctor said it takes a while to know. So the doctor said come back in 2-3 weeks, but a week after that, I bought a pregnancy test from the store and it said I was not pregnant. I’ve been sleeping a lot and I’ve been having cramps also. I don’t know what to do… My boyfriend believes I’m pregnant because he’s eating a lot more and he’s always sleeping like me. If I am pregnant, I’m keeping my child…

What do you all think about my situation? Do you all think I’m pregnant or something else is wrong?????