Felt uterus at 5 weeks?

Passion💖
My sister told me she felt a ball when she would lay on her stomach since 5 weeks and this is her first pregnancy I'm in my 2nd pregnancy right now and currently 4 weeks and don't feel squat! And in my first pregnancy I don't remember feeling my uterus until I was about 12+ weeks and I'm petite at 4'11 and 115 lbs. Is that too early for her to feel anything?