Yup, I am with the Cookie on this one.
Cheate a situation when you are alone with one parent, so don't start it at the dinner table with everyone around or when your parent is stressed.
How about a mom & daughter trip to the mall or a walk together or a long car ride somewhere or just anytime you are together and no one is likely to disturb you?
Bring across that you really worry about both pregnancy and STDs and want to protect yourself the best that you can. And that your mom's input is important for you
and that you'd appreciate her help in finding a good gyno.
Good info is the key - in addition to what the others have linked to, you'll find a big chunck of links to good sites on contraception in the resources section of "reproduction".
Good onya for wanting to be open about your sexuality with your parents. Wishing you all the best for opening communication!
~spanking new Scarleteen Sexpert~
"We must become the change we want to see."