My last period started on December 11th. I'm not sure when I ovulated because my periods are irregular. On January 3rd, my nipples became very sore and sensitive. Even brushing my arm against them hurts. So I've had that for a few days and today I started cramping. My expected period according to the app is January 15th, but again, they are usually irregular.

Are these possible pregnancy symptoms or is it too soon? I took a frer yesterday and it was negative.