Fundal Height at 6 Weeks

I am pregnant with baby #4. I know typically you shouldn't feel the uterus above the pubic bone very much prior to 10 weeks. But I, without a doubt, can feel it about 2-3cm above my pubic bone. I have an ultrasound on the 27th because my hcg levels were a bit high but when they did the ultrasound at 5wks there was no yolk sac yet (they said its normal). Anybody know why I can feel it already?

I wasnt asking about bloating. This is my 4th pregnancy, I know the difference.