Gender Baby

Assalamualaikum mummy2 gojes..nk tny la kan, klau 18week punya scan klau dktr kta npk gnder mcm gulz mummy smua rsa blh caya ka? Or nt perut mkin besar blh tukar gender len..? Sbb yela kan msih awl 18w5d,klau scan awl2 nie nampak telur dh tentu2 boy?, klau awal2 nie scan npk mcm gegulz mummy smua rsa mcm mna? Hari tu sy ada beli test gender guna urine, klau blue line boy, klau red line it's a gulz, sy test nek red line.. Pendapat mummy?