Prenatal

I just took a positive pregnancy test yesterday. I scheduled my first check and they told me I could just take flinestones vitamins. I am already freaking out that I'm doing everything wrong and I can't be more than two weeks pregnant...is it ok to just take those or should I get an over the counter prenatal? If so, any recommendations on a brand? I haven't ever taken any and everything I'm reading says you should take them before you're even pregnant. Now of course I am scared. Any advice all around?