Needing opinions on first ultrsound

sm19

Hello ladies, im needing opinions here. First time pregnant so im always nervous.

I went for my first ulttasound today to which we discussed i should be 7 weeks 5 days..and the gyno said after the ultrasound. that either its alot younger or preparing to be rejected. All i saw was a white ball within a black oval in my uterus... im a bit confused ... i have to go back in 2 weeks.

He also didnt refill my prenatals as he said that ive taken 3 months so far and it was enough for now. and later on in the pregnancy he'd ask me to start taking them again. Is that normal?