You will never find the right time because such a thing doesn't exist. Either blurt it out, or, if you can't, start seeking medical care by yourself. In your state, can you go to Planned parenthood without informing your parents?

If you hope to carry to term, as a teen, you probably should be with Planned Parenthood, because they provide prenatal care to young girls all the time. OB-GYNs in private practice these days are dealing with 30+ year old women who have very different issues in their pregnancies. So PP is better. On the other hand, if you have been taking psych meds, and are considering having a baby, you need to have your pdoc and ob-gyn talk betwixt each other to help you make a call, because it is a tough call, and you might need an ob-gyn who specializes in caring for pregnant psych patients.

Are you at least normal weight for your age? Are your hips wider than your waist? Hav3 you been eating well for the past few months? Are you taking prenatal vitamins? I think you ne3d 800 mg of folate in the first trimester, to prevent neural tube defects... this is a tough one... as someone said, have a talk with your school counselor who I am sure knows how to help pregnant teens navigate the health care system, talk to parents, etc.

If you are taking psych drugs, look up whether they are teratogenic.