What to do???

I’m NOT ready for a baby, not at all. But, my soon-to-be- mother-in-law believes I’m pregnant. My periods 3 days late, I’ve been having “morning sickness” for about a week now but it’s only at night (9pm-4am), my boobs aren’t just sore... they’re TIGHT and PLUMP, I’m overly emotional (I’m not emotional on my period) I forget EVERYTHING!! But all the tests say “negative”. I’m not showing any normal signs of my period. Oh and certain smells make me sick, and I’ve never had a weak stomach. (I was always the one to change the dirty diapers that made my mom who was pregnant at the time lose her lunch). I’m just stuck, idk what I need to do. Neither of us, my fiancé or myself, want a baby right now. But we understand that it’s not up to us, it’s god plan. ADVICE?? 😭