How do you know that you are pregnant?

I'm missing period almost 5 month.. 3 month early already check prenancy test but negative, already check clinic also, 2 swasta and 1 gov.. still negative result.. after 4 month my belly more bigger.. I'm just scared it's was cancer or another sickness .. I'm go another swasta clinic.. Alhamdulillah got little heart beat 💕 then their nurse say why to late buat Buku 😆 ..mereka tak tahu.. yg I pon baru tahu hahahaha