Fiance thinks I'm pregnant.

So this is tmi but my fiance think I'm pregnant because my nips have gotten bigger. I keep getting headaches and I'm peeing like crazy during the night. I keep telling him we wont know until I miss my period but I dont want him getting his Hope's up im really worried right now does anyone know what else I could say to him. he called his mother yesterday and talk to her and told her what was going on and she thinks I could be and he got her all excited. What if I'm not. Im going to disappoint them. I'm so scared.