Couldn’t see the placenta?

I had my first US at 11w3days I’m 12 weeks now. Doctor just called and said they want me in to schedule another US soon because they couldn’t see the placenta and want to make sure it’s not placenta previa. Of course now I’m freaking out and googling what they could me 😹🤦🏻‍♀️ anyone been told at around 11 weeks that they couldn’t see the placenta and everything was still fine? I also have a tilted uterus so could that make it harder to see as well?