Eh ada la, nausea tanpa muntah tu mmg common dalam pregnancy, especially yang first trimester sampai mid-pregnancy gitu. Few of my mum friends also ada stage macam tu, rasa loya je tapi tak keluar, so annoying kan! Could be hormones still doing their thing, or maybe makanan tertentu yang trigger, try makan smaller portions, frequent snacking, dan kurang yang heavy/greasy. Tapi since 18 weeks pun still ada, better check with your doc just to make sure everything's okay and maybe dia boleh suggest meds yang safe during pregnancy, ada beberapa options yang really help!