ultrasounds that late can be off, I had one at 38 weeks and they told me she was over 7 and a half pounds and being diabetic I figured she would be big but 2 days later I had her she was only 6 pounds 13 ounces...I bought a few newborn sizes that she fit into for a few weeks and brought a smaller and bigger size with me to the hospital just in case.

Thanks @sgtpeppertheory. I was just thinking about bringing different size hehe

I wouldn't worry. ultrasounds can be off by 2 pounds sometimes. i think even if she was 8 lbs newborn clothes should still fit but maybe she wouldn't wear them as long as a 6 lbs baby would.(-: just bring different size clothes with you just in case!