ultrasound questions

Hi.I am considered to be high risk due to having high blood pressure (found 2 years before pregnancy).I am also 19, overweight (weight 260) and my grandma is a twin, so I could possibly have twins. However, I am approximately 8 weeks pregnant and my first appt isnt until 11 weeks. With that being sai, my doctor said no ultrasound will be done until 16 weeks.Is there any way I can get one before then or no? I see people on here having them at 6 to 8 weeks?

Thanks in advance foe the help!